diff --git a/C4/C4.puml b/C4/C4.puml
index ca940875..755acd22 100644
--- a/C4/C4.puml
+++ b/C4/C4.puml
@@ -4,7 +4,7 @@
 ' ##################################
 !function C4Version()
   ' 2 spaces and ' are used as unique marker, that the release scripts makes the correct version update
-  !$c4Version  =  "2.7.0"
+  !$c4Version  =  "2.8.0"
   !return $c4Version
 !end function
 
@@ -53,11 +53,17 @@ rectangle C4VersionDetailsArea <<legendArea>> [
 !$LEGEND_DOTTED_LINE ?= "dotted"
 !$LEGEND_DASHED_LINE ?= "dashed"
 !$LEGEND_BOLD_LINE ?= "bold"
+!$LEGEND_SOLID_LINE ?= "solid"
+
 !$LEGEND_BOUNDARY ?= "boundary"
-!$LEGEND_DASHED_BOUNDARY ?= "dashed"
-' ignore transparent atm, that the legend is smaller
-'$LEGEND_DASHED_TRANSPARENT_BOUNDARY ?= "dashed, transparent"
-!$LEGEND_DASHED_TRANSPARENT_BOUNDARY ?= "dashed"
+' ignore (boundary) transparent atm, that the legend is smaller
+' !$LEGEND_BOUNDARY_TRANSPARENT_INCL_COMA ?= "transparent, "
+!$LEGEND_BOUNDARY_TRANSPARENT_INCL_COMA ?= ""
+' (boundary) dashed should not be ignored atm
+!$LEGEND_BOUNDARY_DASHED_INCL_COMA ?= "dashed, "
+' !$LEGEND_BOUNDARY_DASHED_INCL_COMA ?= ""
+
+!$LEGEND_THICKNESS ?= "thickness"
 
 !$SKETCH_FOOTER_WARNING ?= "Warning:"
 !$SKETCH_FOOTER_TEXT ?= "Created for discussion, needs to be validated"
@@ -101,6 +107,8 @@ rectangle C4VersionDetailsArea <<legendArea>> [
 !global $DOTTED_LINE = "dotted"
 !global $DASHED_LINE = "dashed"
 !global $BOLD_LINE = "bold"
+' solid is not defined in plantUML, but works as reset of all other styles too
+!global $SOLID_LINE = "solid"
 
 !global $LEGEND_DETAILS_NONE = "none"
 !global $LEGEND_DETAILS_NORMAL = "normal"
@@ -314,7 +322,7 @@ skinparam package {
   !return ""
 !endfunction
 
-!function $elementTagSkinparams($element, $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape)
+!function $elementTagSkinparams($element, $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $borderStyle, $borderThickness)
   !$elementSkin = "skinparam " + $element + "<<" + $tagStereo + ">> {" + %newline()
   !if ($fontColor != "")
     !if (%strpos($tagStereo, "boundary") < 0)
@@ -344,22 +352,28 @@ skinparam package {
       !$elementSkin = $elementSkin + "    DiagonalCorner " + $EIGHT_SIDED_SIZE+ %newline()
     !endif
   !endif
+  !if ($borderStyle != "")
+    !$elementSkin = $elementSkin + "    BorderStyle " + $borderStyle + %newline()
+  !endif
+  !if ($borderThickness != "")
+    !$elementSkin = $elementSkin + "    BorderThickness " + $borderThickness + %newline()
+  !endif
   !$elementSkin = $elementSkin + "}" + %newline()
   !return $elementSkin
 !endfunction
 
-!unquoted procedure $defineSkinparams($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape)
+!unquoted procedure $defineSkinparams($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $borderStyle, $borderThickness)
   ' only rectangle supports shape(d corners)
-  !$tagSkin = $elementTagSkinparams("rectangle", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape)
-  !$tagSkin = $tagSkin + $elementTagSkinparams("database", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "")
-  !$tagSkin = $tagSkin + $elementTagSkinparams("queue", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "")
+  !$tagSkin = $elementTagSkinparams("rectangle", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $borderStyle, $borderThickness)
+  !$tagSkin = $tagSkin + $elementTagSkinparams("database", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "", $borderStyle, $borderThickness)
+  !$tagSkin = $tagSkin + $elementTagSkinparams("queue", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "", $borderStyle, $borderThickness)
   ' plantuml.jar bug - actor have to be after person
-  !$tagSkin = $tagSkin + $elementTagSkinparams("person", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "")
+  !$tagSkin = $tagSkin + $elementTagSkinparams("person", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "", $borderStyle, $borderThickness)
   ' actor has style awesome, therefore $fontColor is ignored and text uses $bgColor too
-  !$tagSkin = $tagSkin + $elementTagSkinparams("actor", $tagStereo, $bgColor, $bgColor, $borderColor, $shadowing, "")
+  !$tagSkin = $tagSkin + $elementTagSkinparams("actor", $tagStereo, $bgColor, $bgColor, $borderColor, $shadowing, "", $borderStyle, $borderThickness)
   ' sequence requires participant
-  !$tagSkin = $tagSkin + $elementTagSkinparams("participant", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "")
-  !$tagSkin = $tagSkin + $elementTagSkinparams("sequencebox", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "")
+  !$tagSkin = $tagSkin + $elementTagSkinparams("participant", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "", $borderStyle, $borderThickness)
+  !$tagSkin = $tagSkin + $elementTagSkinparams("sequencebox", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, "", $borderStyle, $borderThickness)
   !if (%strpos($tagStereo, "boundary") >= 0 && $bgColor != "")
     !$tagSkin = $tagSkin + "skinparam package<<" + $tagStereo + ">>StereotypeFontColor " + $bgColor + %newline()
     !$tagSkin = $tagSkin + "skinparam rectangle<<" + $tagStereo + ">>StereotypeFontColor " + $bgColor + %newline()
@@ -447,7 +461,7 @@ $elementSkin
   !return "1"
 !endfunction
 
-!function $tagLegendMask($bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite)
+!function $tagLegendMask($bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $borderStyle, $borderThickness)
   !$mask = ""
   !$mask = $addMaskFlag($mask, $bgColor)
   !$mask = $addMaskFlag($mask, $fontColor)
@@ -455,11 +469,13 @@ $elementSkin
   !$mask = $addMaskFlag($mask, $shadowing)
   !$mask = $addMaskFlag($mask, $shape)
   !$mask = $addMaskFlag($mask, $sprite)
+  !$mask = $addMaskFlag($mask, $borderStyle)
+  !$mask = $addMaskFlag($mask, $borderThickness)
   !return $mask
 !endfunction
 
 !function $resetMask()
-  !return "000000"
+  !return "00000000"
 !endfunction
 
 !function $combineMasks($mask1, $mask2)
@@ -470,6 +486,8 @@ $elementSkin
   !$mask = $mask + $orFlags(%substr($mask1, 3, 1), %substr($mask2, 3, 1))
   !$mask = $mask + $orFlags(%substr($mask1, 4, 1), %substr($mask2, 4, 1))
   !$mask = $mask + $orFlags(%substr($mask1, 5, 1), %substr($mask2, 5, 1))
+  !$mask = $mask + $orFlags(%substr($mask1, 6, 1), %substr($mask2, 6, 1))
+  !$mask = $mask + $orFlags(%substr($mask1, 7, 1), %substr($mask2, 7, 1))
   !return $mask
 !endfunction
 
@@ -511,7 +529,7 @@ $elementSkin
   !return $formatted
 !endfunction
 
-!function $setTagLegendVariables($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $legendText, $legendSprite)
+!function $setTagLegendVariables($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $legendText, $legendSprite, $borderStyle, $borderThickness)
   !$bg = $bgColor
   !$fo = $fontColor
   !$bo = $borderColor
@@ -560,32 +578,29 @@ $elementSkin
   !if ($legendSprite != "")
     !$tagEntry = $tagEntry + $getSprite($legendSprite) + " "
   !endif
+
+  !$isBoundary = 0
   !if ($legendText == "")
-    !if ($tagStereo == "boundary")
-      ' #00000000 is transparent
-      !if ($bgColor == "#00000000" || %lower($bgColor) == "transparent")
+    !if (%strpos($tagStereo, "boundary") >= 0)
+      !if ($tagStereo == "boundary")
+        !$isBoundary = 1
         !$tagEntry = $tagEntry + " " + $LEGEND_BOUNDARY + " "
-        !$tagDetails = $tagDetails + $LEGEND_DASHED_TRANSPARENT_BOUNDARY + ", "
       !else
-        !$tagEntry = $tagEntry + " " + $LEGEND_BOUNDARY + " "
-        !$tagDetails = $tagDetails + $LEGEND_DASHED_BOUNDARY + ", "
-      !endif
-    !elseif (%strpos($tagStereo, "boundary") >= 0)
-      ' if contains/ends with _boundary remove _boundary and add "boundary (dashed)"
-      !$pos = %strpos($tagStereo, "_boundary")
-      !if ($pos > 0)
-        !$tagEntry = $tagEntry + " " + %substr($tagStereo, 0 ,$pos)
-        !if ($bgColor == "#00000000" || %lower($bgColor) == "transparent")
-          !$tagEntry = $tagEntry + " " + $LEGEND_BOUNDARY + " "
-          !$tagDetails = $tagDetails + $LEGEND_DASHED_TRANSPARENT_BOUNDARY + ", "
-        !else
-          !$tagEntry = $tagEntry + " " + $LEGEND_BOUNDARY + " "
-          !$tagDetails = $tagDetails + $LEGEND_DASHED_BOUNDARY + ", "
+        ' if contains/ends with _boundary remove _boundary and add "boundary (dashed)"
+        !$pos = %strpos($tagStereo, "_boundary")
+        !if ($pos > 0)
+          !$isBoundary = 1
+          !$tagEntry = $tagEntry + " " + %substr($tagStereo, 0 ,$pos) + " " +$LEGEND_BOUNDARY + " "
         !endif
       !endif
-    !else
+    !endif
+    !if ($isBoundary == 0)
       !$tagEntry = $tagEntry + " " + $tagStereo + " "
     !endif
+
+    !if ($isBoundary == 1 && ($bgColor == "#00000000" || %lower($bgColor) == "transparent"))
+       !$tagDetails = $tagDetails + $LEGEND_BOUNDARY_TRANSPARENT_INCL_COMA
+    !endif
     !if ($shadowing == "true")
       !$tagDetails = $tagDetails + $LEGEND_SHADOW_TEXT + ", "
     !endif
@@ -608,6 +623,26 @@ $elementSkin
         !$tagDetails = $tagDetails + $LEGEND_NO_BG_TEXT + ", "
       !endif
     !endif
+    !if ($borderStyle != "")
+      !if ($borderStyle == $DOTTED_LINE)
+        !$tagDetails = $tagDetails + $LEGEND_DOTTED_LINE + ", "
+      !elseif ($borderStyle == $DASHED_LINE)
+        !if ($isBoundary == 1)
+          !$tagDetails = $tagDetails + $LEGEND_BOUNDARY_DASHED_INCL_COMA
+        !else
+          !$tagDetails = $tagDetails + $LEGEND_DASHED_LINE + ", "
+        !endif
+      !elseif ($borderStyle == $BOLD_LINE)
+        !$tagDetails = $tagDetails + $LEGEND_BOLD_LINE + ", "
+      !elseif ($borderStyle == $SOLID_LINE)
+        !$tagDetails = $tagDetails + $LEGEND_SOLID_LINE + ", "
+      !else
+        !$tagDetails = $tagDetails + $lineStyle + ", "
+      !endif
+    !endif
+    !if ($borderThickness != "")
+      !$tagDetails = $tagDetails + $LEGEND_THICKNESS + " " + $borderThickness + ", "
+    !endif
     !if ($tagDetails=="(" || $tagDetails=="(, ")
       !$tagDetails = "</size>"
     !else
@@ -684,7 +719,7 @@ $elementSkin
       !endif
     !endif
     !if ($lineThickness != "")
-      !$tagDetails = $tagDetails + "thickness " + $lineThickness + ") "
+      !$tagDetails = $tagDetails + $LEGEND_THICKNESS + " " + $lineThickness + ", "
     !endif
     !if ($tagDetails=="(")
       !$tagDetails = "</size>"
@@ -715,14 +750,14 @@ $elementSkin
   !return $tagEntry
 !endfunction
 
-!unquoted procedure $addTagToLegend($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $legendText="", $legendSprite="")
+!unquoted procedure $addTagToLegend($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $legendText="", $legendSprite="", $borderStyle="", $borderThickness="")
 '' if a combined element tag is defined (e.g. "v1.0&v1.1") then it is typically a merged color,
 '' like a new $fontColor="#fdae61" therefore it should be added to the legend
 '' and the & combined tags will be not removed
 '  !if (%strpos($tagStereo, "&") < 0)
-  !$dummyAlreadyVariables = $setTagLegendVariables($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $legendText, $legendSprite)
+  !$dummyAlreadyVariables = $setTagLegendVariables($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $legendText, $legendSprite, $borderStyle, $borderThickness)
   !$tagCustomLegend = $tagCustomLegend + $tagStereo + "\n"
-  !$tagMask = $tagLegendMask( $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite)
+  !$tagMask = $tagLegendMask( $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $borderStyle, $borderThickness)
 %set_variable_value("$" + $tagStereo + "LegendMask", $tagMask)
 '  !endif
 !endprocedure
@@ -788,9 +823,13 @@ $line
 !return $BOLD_LINE
 !endfunction
 
+!function SolidLine()
+!return $SOLID_LINE
+!endfunction
+
 ' used by new defined tags
-!unquoted procedure AddElementTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="")
-$defineSkinparams($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape)
+!unquoted procedure AddElementTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="", $borderStyle="", $borderThickness="")
+$defineSkinparams($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $borderStyle, $borderThickness)
   !if ($sprite!="")
 %set_variable_value("$" + $tagStereo + "ElementTagSprite", $sprite)
     !if ($legendSprite == "")
@@ -800,10 +839,10 @@ $defineSkinparams($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $s
   !if ($techn != "")
 %set_variable_value("$" + $tagStereo + "ElementTagTechn", $techn)
   !endif
-$addTagToLegend($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $legendText, $legendSprite)
+$addTagToLegend($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
 
-!unquoted procedure $addElementTagInclReuse($elementName, $tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="")
+!unquoted procedure $addElementTagInclReuse($elementName, $tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="", $borderStyle="", $borderThickness="")
   !$bgColor=$restoreEmpty($elementName, "bgColor", $bgColor, %false())
   !$fontColor=$restoreEmpty($elementName, "fontColor", $fontColor, %false())
   !$borderColor=$restoreEmpty($elementName, "borderColor", $borderColor, %false())
@@ -814,8 +853,10 @@ $addTagToLegend($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $sha
   ' new style should has its own legend text
   ' !$legendText=$restoreEmpty($elementName, "legendText", $legendText, %false())
   !$legendSprite=$restoreEmpty($elementName, "legendSprite", $legendSprite, %false())
+  !$borderStyle=$restoreEmpty($elementName, "borderStyle", $borderStyle, %false())
+  !$borderThickness=$restoreEmpty($elementName, "borderThickness", $borderThickness, %false())
 
-  AddElementTag($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite)
+  AddElementTag($tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
 
 ' used by new defined rel tags
@@ -835,7 +876,7 @@ $addRelTagToLegend($tagStereo, $textColor, $lineColor, $lineStyle, $legendText,
 !endprocedure
 
 ' update the style of existing elements like person, ...
-!unquoted procedure UpdateElementStyle($elementName, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="")
+!unquoted procedure UpdateElementStyle($elementName, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="", $borderStyle="", $borderThickness="")
 !$bgColor=$restoreEmpty($elementName, "bgColor", $bgColor, %true())
 !$fontColor=$restoreEmpty($elementName, "fontColor", $fontColor, %true())
 !$borderColor=$restoreEmpty($elementName, "borderColor", $borderColor, %true())
@@ -845,7 +886,10 @@ $addRelTagToLegend($tagStereo, $textColor, $lineColor, $lineStyle, $legendText,
 !$techn=$restoreEmpty($elementName, "techn", $techn, %true())
 !$legendText=$restoreEmpty($elementName, "legendText", $legendText, %true())
 !$legendSprite=$restoreEmpty($elementName, "legendSprite", $legendSprite, %true())
-$defineSkinparams($elementName, $bgColor, $fontColor, $borderColor, $shadowing, $shape)
+!$borderStyle=$restoreEmpty($elementName, "borderStyle", $borderStyle, %true())
+!$borderThickness=$restoreEmpty($elementName, "borderThickness", $borderThickness, %true())
+
+$defineSkinparams($elementName, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $borderStyle, $borderThickness)
   !if ($sprite != "")
 %set_variable_value("$" + $elementName + "ElementTagSprite", $sprite)
     !if ($legendSprite == "")
@@ -855,9 +899,9 @@ $defineSkinparams($elementName, $bgColor, $fontColor, $borderColor, $shadowing,
   !if ($techn != "")
 %set_variable_value("$" + $elementName + "ElementTagTechn", $techn)
   !endif
-  !$dummyAlreadyVariables = $setTagLegendVariables($elementName, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $legendText, $legendSprite)
+  !$dummyAlreadyVariables = $setTagLegendVariables($elementName, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $legendText, $legendSprite, $borderStyle, $borderThickness)
   ' default tags sets at least bgColor and fontColor
-  !$tagMask = $tagLegendMask("CHANGED", "CHANGED", $borderColor, $shadowing, $shape, $sprite)
+  !$tagMask = $tagLegendMask("CHANGED", "CHANGED", $borderColor, $shadowing, $shape, $sprite, $borderStyle, $borderThickness)
 %set_variable_value("$" + $elementName + "LegendMask", $tagMask)
 !endprocedure
 
@@ -1237,22 +1281,22 @@ $getLegendArea($alias, $hideStereotype, $details)
 ' Boundaries
 ' ##################################
 
-!unquoted procedure UpdateBoundaryStyle($elementName="", $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $type="", $legendText="")
+!unquoted procedure UpdateBoundaryStyle($elementName="", $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $type="", $legendText="", $borderStyle="", $borderThickness="")
   !if ($elementName != "")
     !$elementBoundary = $elementName + '_boundary'
-    UpdateElementStyle($elementBoundary, $bgColor, $fontColor, $borderColor, $shadowing, $shape, "", $type, $legendText, "")
+    UpdateElementStyle($elementBoundary, $bgColor, $fontColor, $borderColor, $shadowing, $shape, "", $type, $legendText, "", $borderStyle, $borderThickness)
   !else
-    UpdateElementStyle("boundary", $bgColor, $fontColor, $borderColor, $shadowing, $shape, "", $type, $legendText, "")
+    UpdateElementStyle("boundary", $bgColor, $fontColor, $borderColor, $shadowing, $shape, "", $type, $legendText, "", $borderStyle, $borderThickness)
     ' simulate color inheritance
-    UpdateBoundaryStyle("enterprise", $bgColor, $fontColor, $borderColor, $shadowing, $shape, "Enterprise", "")
-    UpdateBoundaryStyle("system", $bgColor, $fontColor, $borderColor, $shadowing, $shape, "System", "")
-    UpdateBoundaryStyle("container", $bgColor, $fontColor, $borderColor, $shadowing, $shape, "Container", "")
+    UpdateBoundaryStyle("enterprise", $bgColor, $fontColor, $borderColor, $shadowing, $shape, "Enterprise", "", $borderStyle, $borderThickness)
+    UpdateBoundaryStyle("system", $bgColor, $fontColor, $borderColor, $shadowing, $shape, "System", "", $borderStyle, $borderThickness)
+    UpdateBoundaryStyle("container", $bgColor, $fontColor, $borderColor, $shadowing, $shape, "Container", "", $borderStyle, $borderThickness)
   !endif
 !endprocedure
 
-!unquoted procedure AddBoundaryTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $type="", $legendText="")
+!unquoted procedure AddBoundaryTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $type="", $legendText="", $borderStyle="", $borderThickness="")
     !$tagBoundary = $tagStereo + '_boundary'
-    AddElementTag($tagBoundary, $bgColor, $fontColor, $borderColor, $shadowing, $shape, "", $type, $legendText, "")
+    AddElementTag($tagBoundary, $bgColor, $fontColor, $borderColor, $shadowing, $shape, "", $type, $legendText, "", $borderStyle, $borderThickness)
 !endprocedure
 
 ' add _boundary to all tags that short tag version can be used
@@ -1291,7 +1335,7 @@ rectangle "$getBoundary($label, $type)" $toStereos("boundary", $boundaryTags) as
 !endprocedure
 
 ' Boundary Styling
-UpdateBoundaryStyle("", $bgColor=$BOUNDARY_BG_COLOR, $fontColor=$BOUNDARY_COLOR, $borderColor=$BOUNDARY_COLOR)
+UpdateBoundaryStyle("", $bgColor=$BOUNDARY_BG_COLOR, $fontColor=$BOUNDARY_COLOR, $borderColor=$BOUNDARY_COLOR, $borderStyle=DashedLine())
 
 ' Index
 ' ##################################
diff --git a/C4/C4_Component.puml b/C4/C4_Component.puml
index 8c7e9150..c0934809 100644
--- a/C4/C4_Component.puml
+++ b/C4/C4_Component.puml
@@ -23,11 +23,11 @@ UpdateElementStyle("component", $COMPONENT_BG_COLOR, $COMPONENT_FONT_COLOR, $COM
 UpdateElementStyle("external_component", $EXTERNAL_COMPONENT_BG_COLOR, $EXTERNAL_COMPONENT_FONT_COLOR, $EXTERNAL_COMPONENT_BORDER_COLOR)
 
 ' shortcuts with default colors
-!unquoted procedure AddComponentTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="")
-  $addElementTagInclReuse("component", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite)
+!unquoted procedure AddComponentTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="", $borderStyle="", $borderThickness="")
+  $addElementTagInclReuse("component", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
-!unquoted procedure AddExternalComponentTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="")
-  $addElementTagInclReuse("external_component", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite)
+!unquoted procedure AddExternalComponentTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="", $borderStyle="", $borderThickness="")
+  $addElementTagInclReuse("external_component", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
 
 ' Layout
diff --git a/C4/C4_Container.puml b/C4/C4_Container.puml
index f584f837..afafcef1 100644
--- a/C4/C4_Container.puml
+++ b/C4/C4_Container.puml
@@ -28,15 +28,15 @@ UpdateElementStyle("external_container", $EXTERNAL_CONTAINER_BG_COLOR, $EXTERNAL
 UpdateBoundaryStyle("container", $bgColor=$CONTAINER_BOUNDARY_BG_COLOR, $fontColor=$CONTAINER_BOUNDARY_COLOR, $borderColor=$CONTAINER_BOUNDARY_COLOR, $type="Container")
 
 ' shortcuts with default colors
-!unquoted procedure AddContainerTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="")
-  $addElementTagInclReuse("container", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite)
+!unquoted procedure AddContainerTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="", $borderStyle="", $borderThickness="")
+  $addElementTagInclReuse("container", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
-!unquoted procedure AddExternalContainerTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="")
-  $addElementTagInclReuse("external_container", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite)
+!unquoted procedure AddExternalContainerTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $techn="", $legendText="", $legendSprite="", $borderStyle="", $borderThickness="")
+  $addElementTagInclReuse("external_container", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $techn, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
 
-!unquoted procedure UpdateContainerBoundaryStyle($bgColor=$CONTAINER_BOUNDARY_BG_COLOR, $fontColor=$CONTAINER_BOUNDARY_COLOR, $borderColor=$CONTAINER_BOUNDARY_COLOR, $shadowing="", $shape="", $type="Container", $legendText="")
-  UpdateBoundaryStyle("container", $bgColor, $fontColor, $borderColor, $shadowing, $shape, $type, $legendText)
+!unquoted procedure UpdateContainerBoundaryStyle($bgColor=$CONTAINER_BOUNDARY_BG_COLOR, $fontColor=$CONTAINER_BOUNDARY_COLOR, $borderColor=$CONTAINER_BOUNDARY_COLOR, $shadowing="", $shape="", $type="Container", $legendText="", $borderStyle="", $borderThickness="")
+  UpdateBoundaryStyle("container", $bgColor, $fontColor, $borderColor, $shadowing, $shape, $type, $legendText, $borderStyle, $borderThickness)
 !endprocedure
 
 ' Layout
diff --git a/C4/C4_Context.puml b/C4/C4_Context.puml
index 5a6b22fe..32a84415 100644
--- a/C4/C4_Context.puml
+++ b/C4/C4_Context.puml
@@ -44,24 +44,24 @@ UpdateBoundaryStyle("system", $bgColor=$SYSTEM_BOUNDARY_BG_COLOR, $fontColor=$SY
 UpdateBoundaryStyle("enterprise", $bgColor=$ENTERPRISE_BOUNDARY_BG_COLOR, $fontColor=$ENTERPRISE_BOUNDARY_COLOR, $borderColor=$ENTERPRISE_BOUNDARY_COLOR, $type="Enterprise")
 
 ' shortcuts with default colors
-!unquoted procedure AddPersonTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $legendText="", $legendSprite="", $type="")
-  $addElementTagInclReuse("person", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite)
+!unquoted procedure AddPersonTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $legendText="", $legendSprite="", $type="", $borderStyle="", $borderThickness="")
+  $addElementTagInclReuse("person", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
-!unquoted procedure AddExternalPersonTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $legendText="", $legendSprite="", $type="")
-  $addElementTagInclReuse("external_person", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite)
+!unquoted procedure AddExternalPersonTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $legendText="", $legendSprite="", $type="", $borderStyle="", $borderThickness="")
+  $addElementTagInclReuse("external_person", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
-!unquoted procedure AddSystemTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $legendText="", $legendSprite="", $type="")
-  $addElementTagInclReuse("system", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite)
+!unquoted procedure AddSystemTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $legendText="", $legendSprite="", $type="", $borderStyle="", $borderThickness="")
+  $addElementTagInclReuse("system", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
-!unquoted procedure AddExternalSystemTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $legendText="", $legendSprite="", $type="")
-  $addElementTagInclReuse("external_system", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite)
+!unquoted procedure AddExternalSystemTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $legendText="", $legendSprite="", $type="", $borderStyle="", $borderThickness="")
+  $addElementTagInclReuse("external_system", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite, $borderStyle, $borderThickness)
 !endprocedure
 
-!unquoted procedure UpdateEnterpriseBoundaryStyle($bgColor=$ENTERPRISE_BOUNDARY_BG_COLOR, $fontColor=$ENTERPRISE_BOUNDARY_COLOR, $borderColor=$ENTERPRISE_BOUNDARY_COLOR, $shadowing="", $shape="", $type="Enterprise", $legendText="")
-  UpdateBoundaryStyle("enterprise", $bgColor, $fontColor, $borderColor, $shadowing, $shape, $type, $legendText)
+!unquoted procedure UpdateEnterpriseBoundaryStyle($bgColor=$ENTERPRISE_BOUNDARY_BG_COLOR, $fontColor=$ENTERPRISE_BOUNDARY_COLOR, $borderColor=$ENTERPRISE_BOUNDARY_COLOR, $shadowing="", $shape="", $type="Enterprise", $legendText="", $borderStyle="", $borderThickness="")
+  UpdateBoundaryStyle("enterprise", $bgColor, $fontColor, $borderColor, $shadowing, $shape, $type, $legendText, $borderStyle, $borderThickness)
 !endprocedure
-!unquoted procedure UpdateSystemBoundaryStyle($bgColor=$SYSTEM_BOUNDARY_BG_COLOR, $fontColor=$SYSTEM_BOUNDARY_COLOR, $borderColor=$SYSTEM_BOUNDARY_COLOR, $shadowing="", $shape="", $type="System", $legendText="")
-  UpdateBoundaryStyle("system", $bgColor, $fontColor, $borderColor, $shadowing, $shape, $type, $legendText)
+!unquoted procedure UpdateSystemBoundaryStyle($bgColor=$SYSTEM_BOUNDARY_BG_COLOR, $fontColor=$SYSTEM_BOUNDARY_COLOR, $borderColor=$SYSTEM_BOUNDARY_COLOR, $shadowing="", $shape="", $type="System", $legendText="", $borderStyle="", $borderThickness="")
+  UpdateBoundaryStyle("system", $bgColor, $fontColor, $borderColor, $shadowing, $shape, $type, $legendText, $borderStyle, $borderThickness)
 !endprocedure
 
 ' Sprites
diff --git a/C4/C4_Deployment.puml b/C4/C4_Deployment.puml
index 8355631d..2d51fa0d 100644
--- a/C4/C4_Deployment.puml
+++ b/C4/C4_Deployment.puml
@@ -24,9 +24,9 @@ skinparam rectangle<<node>> {
 
 ' shortcuts with default colors
 ' node specific: $techn is only used in old scripts, new scripts uses $type ($techn has to remain, it could be called via named argument)
-!unquoted procedure AddNodeTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $type="", $legendText="", $legendSprite="", $techn="")
+!unquoted procedure AddNodeTag($tagStereo, $bgColor="", $fontColor="", $borderColor="", $shadowing="", $shape="", $sprite="", $type="", $legendText="", $legendSprite="", $techn="", $borderStyle="", $borderThickness="")
   !$type=$type+$techn
-  $addElementTagInclReuse("node", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite)
+  $addElementTagInclReuse("node", $tagStereo, $bgColor, $fontColor, $borderColor, $shadowing, $shape, $sprite, $type, $legendText, $legendSprite, "", $borderStyle, $borderThickness)
 !endprocedure
 
 ' Layout
diff --git a/C4/C4_Dynamic.puml b/C4/C4_Dynamic.puml
index 8e81cd3b..6b7317f1 100644
--- a/C4/C4_Dynamic.puml
+++ b/C4/C4_Dynamic.puml
@@ -30,10 +30,14 @@ $getRel($direction, $alias1, $alias2, $e_index + ": " + $label, $techn, "", "",
 
 ' all RelIndex... calls are outdated, Rel(..., $index=...) calls should be used !!!!
 
+' first Rel() supports the $index argument too; second Rel() overwrites C4.puml definition
 !unquoted procedure Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
 !$pre = $getPrefix($index)
 $getRel("-->>", $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
 !unquoted procedure RelIndex($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel("-->>", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
@@ -42,6 +46,9 @@ $getRel("-->>", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $
 !$pre = $getPrefix($index)
 $getRel("<<--", $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel_Back($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_Back($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
 !unquoted procedure RelIndex_Back($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel("<<--", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
@@ -50,6 +57,9 @@ $getRel("<<--", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $
 !$pre = $getPrefix($index)
 $getRel("->>", $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel_Neighbor($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_Neighbor($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
 !unquoted procedure RelIndex_Neighbor($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel("->>", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
@@ -58,6 +68,9 @@ $getRel("->>", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $t
 !$pre = $getPrefix($index)
 $getRel("<<-", $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel_Back_Neighbor($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_Back_Neighbor($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
 !unquoted procedure RelIndex_Back_Neighbor($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel("<<-", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
@@ -66,10 +79,16 @@ $getRel("<<-", $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $t
 !$pre = $getPrefix($index)
 $getRel($down("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel_D($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_D($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
 !unquoted procedure Rel_Down($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
 !$pre = $getPrefix($index)
 $getRel($down("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel_Down($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_Down($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
 !unquoted procedure RelIndex_D($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel($down("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
@@ -81,10 +100,16 @@ $getRel($down("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr,
 !$pre = $getPrefix($index)
 $getRel($up("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel_U($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_U($from, $to, $label, $techn, $descr, $sprite, $tags, $link=, "")
+!endprocedure
 !unquoted procedure Rel_Up($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
 !$pre = $getPrefix($index)
 $getRel($up("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel_Up($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_Up($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
 !unquoted procedure RelIndex_U($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel($up("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
@@ -96,9 +121,15 @@ $getRel($up("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $s
 !$pre = $getPrefix($index)
 $getRel($left("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
-!unquoted procedure Rel_Left($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+!unquoted procedure Rel_L($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_L($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
+!unquoted procedure Rel_Left($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
 !$pre = $getPrefix($index)
-$getRel($left("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link, $index="")
+$getRel($left("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+!unquoted procedure Rel_Left($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_Left($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
 !endprocedure
 !unquoted procedure RelIndex_L($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel($left("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
@@ -111,10 +142,16 @@ $getRel($left("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr,
 !$pre = $getPrefix($index)
 $getRel($right("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel_R($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_R($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
 !unquoted procedure Rel_Right($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="")
 !$pre = $getPrefix($index)
 $getRel($right("-","->>"), $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
+!unquoted procedure Rel_Right($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel_Right($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "")
+!endprocedure
 !unquoted procedure RelIndex_R($e_index, $from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
 $getRel($right("-","->>"), $from, $to, $e_index + ": " + $label, $techn, $descr, $sprite, $tags, $link)
 !endprocedure
diff --git a/C4/C4_Sequence.puml b/C4/C4_Sequence.puml
new file mode 100644
index 00000000..1445b869
--- /dev/null
+++ b/C4/C4_Sequence.puml
@@ -0,0 +1,393 @@
+!include <C4/C4_Component>
+
+' Scope: Interactions in an enterprise, software system or container.
+' Primary and supporting elements: Depends on the diagram scope -
+'     enterprise - people and software systems Related to the enterprise in scope
+'     software system - see system context or container diagrams,
+'     container - see component diagram.
+' Intended audience: Technical and non-technical people, inside and outside of the software development team.
+
+' Sequence diagram introduces (automatically) numbered interactions:
+'     (lowercase) increment($offset=1): increase current index (procedure which has no direct output)
+'     (lowercase) setIndex($new_index): set the new index (procedure which has no direct output)
+'
+'     (Uppercase) LastIndex(): return the last used index (function which can be used as argument)
+'     (Uppercase) Index($offset=1): returns current index and calculates next index (function which can be used as argument)
+'     (Uppercase) SetIndex($new_index): returns new set index and calculates next index (function which can be used as argument)
+
+' enables multi-level boxes
+!pragma teoz true
+
+
+' Legend redefintion
+' ##################################
+' sequence has no dashed boxes
+!if ($LEGEND_DASHED_BOUNDARY == "dashed")
+  !$LEGEND_DASHED_BOUNDARY = ""
+!endif
+!if ($LEGEND_DASHED_TRANSPARENT_BOUNDARY == "dashed")
+  !$LEGEND_DASHED_TRANSPARENT_BOUNDARY = ""
+!endif
+UpdateBoundaryStyle("", $bgColor=$BOUNDARY_BG_COLOR, $fontColor=$BOUNDARY_COLOR, $borderColor=$BOUNDARY_COLOR)
+UpdateBoundaryStyle("enterprise", $bgColor=$ENTERPRISE_BOUNDARY_BG_COLOR, $fontColor=$ENTERPRISE_BOUNDARY_COLOR, $borderColor=$ENTERPRISE_BOUNDARY_COLOR, $type="Enterprise")
+UpdateBoundaryStyle("system", $bgColor=$SYSTEM_BOUNDARY_BG_COLOR, $fontColor=$SYSTEM_BOUNDARY_COLOR, $borderColor=$SYSTEM_BOUNDARY_COLOR, $type="System")
+UpdateBoundaryStyle("container", $bgColor=$CONTAINER_BOUNDARY_BG_COLOR, $fontColor=$CONTAINER_BOUNDARY_COLOR, $borderColor=$CONTAINER_BOUNDARY_COLOR, $type="Container")
+
+' Styling and Layout
+' ##################################
+
+!global $display_element_description = %false()
+
+' typically the element/participant descriptions are not displayed in a sequence diagram, but it can be activated with this call
+!unquoted procedure SHOW_ELEMENT_DESCRIPTIONS($show="true")
+!if ($show == "true")
+  !global $display_element_description = %true()
+!else
+  !global $display_element_description = %false()
+!endif
+!endprocedure
+
+' typically the foot boxes descriptions are not displayed in a sequence diagram, but it can be activated with this call
+!unquoted procedure SHOW_FOOT_BOXES($show="true")
+!if ($show == "true")
+  show footbox
+!else
+  hide footbox
+!endif
+!endprocedure
+
+!global $show_index = %false()
+' All relation specific (default) ordinary index numbers can be shown with this call
+!unquoted procedure SHOW_INDEX($show="true")
+!if ($show == "true")
+  !global $show_index = %true()
+!else
+  !global $show_index = %false()
+!endif
+!endprocedure
+
+' ======= if no theme is defined hide foot box and activate C4_blue styles
+!if (%variable_exists("$THEME"))
+!else
+' $BOUNDARY_BG_COLOR... have to be defined in theme itself that it can be used in styles,...
+' (no default values which are defined in C4.puml) 
+' If skinparams and styles are defined with concrete values no variables are required 
+!$BOUNDARY_BG_COLOR ?= "transparent"
+!$BOUNDARY_COLOR ?= "#444444"
+!$ARROW_COLOR ?= "#666666"
+
+' replace transparent with concrete background that it can be used as font color too
+!if ($BOUNDARY_BG_COLOR == "transparent")
+  !$SEQUENCE_BG_COLOR = white
+!else
+  !$SEQUENCE_BG_COLOR = $BOUNDARY_BG_COLOR
+!endif
+
+' "C4 styled" default is no foot boxes
+hide footbox
+' "C4 styled" default is that lifeline is arrow color
+skinparam SequenceLifelineBorderColor $ARROW_COLOR
+
+skinparam SequenceGroupBodyBackgroundColor $SEQUENCE_BG_COLOR
+skinparam SequenceGroupFontColor $BOUNDARY_COLOR
+skinparam SequenceGroupBackgroundColor $BOUNDARY_COLOR
+skinparam SequenceGroupHeaderFontColor $SEQUENCE_BG_COLOR
+skinparam SequenceGroupBorderColor $BOUNDARY_COLOR
+
+skinparam SequenceReferenceBackgroundColor $SEQUENCE_BG_COLOR
+skinparam SequenceReferenceFontColor $BOUNDARY_COLOR
+skinparam SequenceReferenceHeaderBackgroundColor $BOUNDARY_COLOR
+' VIA STYLE
+' skinparam SequenceReferenceHeaderFontColor $SEQUENCE_BG_COLOR
+<style>
+referenceHeader {
+  fontcolor $SEQUENCE_BG_COLOR
+}
+</style>
+skinparam SequenceReferenceBorderColor $BOUNDARY_COLOR
+
+skinparam SequenceDividerBackgroundColor $SEQUENCE_BG_COLOR
+skinparam SequenceDividerFontColor $BOUNDARY_COLOR
+skinparam SequenceDividerBorderColor $BOUNDARY_COLOR
+
+' VIA STYLE
+' skinparam SequenceDelayFontColor green
+<style>
+sequenceDiagram {
+  delay {
+    FontColor $BOUNDARY_COLOR
+  }
+}
+</style>
+!endif
+' ======= if no theme is defined hide foot box and activate C4_blue styles
+
+' Elements redefinition
+' ##################################
+
+' all elements have to be displayed as participant
+' participants requires ` %newline()` instead of `\n`
+
+!unquoted function $breakWithNewline($text, $lineEnd, $lineStart, $widthStr="-1")
+!$width = %intval($widthStr)
+!$multiLine = ""
+!if (%strpos($text, "\n") >= 0)
+  !while (%strpos($text, "\n") >= 0)
+    !$brPos = %strpos($text, "\n")
+    !if ($brPos > 0)
+      !$multiLine = $multiLine + %substr($text, 0, $brPos) + $lineEnd + %newline() + $lineStart
+    !else
+      ' <U+00A0> non breaking change that newLine breaks with formats can be used with \n\n 
+      !$multiLine = $multiLine + "<U+00A0>" + $lineEnd + %newline() + $lineStart
+    !endif
+    !$text = %substr($text, $brPos+2)
+    !if (%strlen($text) == 0)
+      !$text = "<U+00A0>"
+    !endif
+  !endwhile
+!else
+  !while ($width>0 && %strlen($text) > $width)
+    !$brPos = $width
+    !while ($brPos > 0 && %substr($text, $brPos, 1) != ' ')
+      !$brPos = $brPos - 1
+    !endwhile
+
+    !if ($brPos < 1)
+      !$brPos = %strpos($text, " ")
+    !else
+    !endif
+
+    !if ($brPos > 0)
+      !$multiLine = $multiLine + %substr($text, 0, $brPos) + $lineEnd + %newline() + $lineStart
+      !$text = %substr($text, $brPos + 1)
+    !else
+      !$multiLine = $multiLine+ $text
+      !$text = ""
+    !endif
+  !endwhile
+!endif
+!if (%strlen($text) > 0)
+  !$multiLine = $multiLine + $text
+!endif
+!return $multiLine
+!endfunction
+
+!unquoted function $breakNewLineLabel($text)
+!$multiLine = $breakWithNewline($text, "", "==")
+!return $multiLine
+!endfunction
+
+!unquoted function $breakNewLineDescr($text)
+  !return $breakWithNewline($text, "", "", $REL_DESCR_MAX_CHAR_WIDTH)
+!endfunction
+
+!unquoted function $breakNewLineTechn($text)
+  !$lineStart = "</size>//"
+  !$lineEnd = '//<size:'+$TECHN_FONT_SIZE+'>'
+  !return $breakWithNewline($text, $lineStart, $lineEnd, $REL_TECHN_MAX_CHAR_WIDTH)
+!endfunction
+
+' description is not displayed (size too big, line breaks not supported)
+' properties are not displayed in sequence diagram (size would be too big)
+' $breakLabel() not required by participant
+!procedure $getParticipant($elementType, $alias, $label, $techn, $descr, $sprite, $tags, $link)
+  !$sprite=$toElementArg($sprite, $tags, "ElementTagSprite", $elementType)
+  !$techn=$toElementArg($techn, $tags, "ElementTagTechn", $elementType)
+  !$stereo = $toStereos($elementType,$tags)
+  !$calcLabel = "== " + $breakNewLineLabel($label)
+  !$calcTech = "//<size:" + $TECHN_FONT_SIZE + ">[" + $breakNewLineTechn($techn) + "]</size>//"
+  !$calcDescr = $breakNewLineDescr($descr)
+  !$calcLink = $getLink($link)
+
+participant $alias $stereo $calcLink [
+!if ($sprite != "")
+$getSprite($sprite)
+!endif
+!if ($label != "")
+$calcLabel
+!endif
+!if ($techn != "")
+$calcTech
+!endif
+!if ($display_element_description == %true() && $descr != "")
+
+$calcDescr
+!endif
+]
+!endprocedure
+
+
+!unquoted procedure Person($alias, $label, $descr="", $sprite="", $tags="", $link="", $type="")
+  ' $type reuses $techn definition of $tags
+  $getParticipant("person", $alias, $label, $type, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure Person_Ext($alias, $label, $descr="", $sprite="", $tags="", $link="", $type="")
+  ' $type reuses $techn definition of $tags
+  $getParticipant("external_person", $alias, $label, $type, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure System($alias, $label, $descr="", $sprite="", $tags="", $link="", $type="")
+  ' $type reuses $techn definition of $tags
+  $getParticipant("system", $alias, $label, $type, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure SystemDb($alias, $label, $descr="", $sprite="", $tags="", $link="", $type="")
+  ' $type reuses $techn definition of $tags
+  $getParticipant("system", $alias, $label, $type, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure SystemQueue($alias, $label, $descr="", $sprite="", $tags="", $link="", $type="")
+  ' $type reuses $techn definition of $tags
+  $getParticipant("system", $alias, $label, $type, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure System_Ext($alias, $label, $descr="", $sprite="", $tags="", $link="", $type="")
+  ' $type reuses $techn definition of $tags
+  $getParticipant("external_system", $alias, $label, $type, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure SystemDb_Ext($alias, $label, $descr="", $sprite="", $tags="", $link="", $type="")
+  ' $type reuses $techn definition of $tags
+  $getParticipant("external_system", $alias, $label, $type, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure SystemQueue_Ext($alias, $label, $descr="", $sprite="", $tags="", $link="", $type="")
+  ' $type reuses $techn definition of $tags
+  $getParticipant("external_system", $alias, $label, $type, $descr, $sprite, $tags, $link)
+!endprocedure
+
+
+
+!unquoted procedure Container($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("container", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure ContainerDb($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("container", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure ContainerQueue($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("container", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure Container_Ext($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("external_container", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure ContainerDb_Ext($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("external_container", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure ContainerQueue_Ext($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("external_container", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+
+
+!unquoted procedure Component($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("component", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure ComponentDb($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("component", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure ComponentQueue($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("component", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure Component_Ext($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("external_component", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure ComponentDb_Ext($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("external_component", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+!unquoted procedure ComponentQueue_Ext($alias, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+  $getParticipant("external_component", $alias, $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+
+
+' Boundary redefinition
+' ##################################
+
+' all boundaries have to be displayed as box and 
+' !!! important changes: without { at the end; and boundary ends with Boundary_End() instead of }
+
+' alias ignored
+' $breakLabel() not required by participant
+
+!unquoted procedure Boundary($alias, $label, $type="", $tags="", $link="")
+!$boundaryTags = $addBoundaryPostfix($tags)
+' nodes $type reuses $techn definition of $boundaryTags
+!$type=$toElementArg($type, $boundaryTags, "ElementTagTechn", "boundary")
+!if ($link != "")
+  !$usedNewLine = ']]\n== [[' + $link + ' '
+  !$labelType = '== [[' + $link + ' ' + $breakText($label, $usedNewLine) + ']]'
+!else
+  !$usedNewLine = '\n== '
+  !$labelType = $breakText($label, $usedNewLine)
+!endif
+!if (type != "")
+    !$labelType = $labelType + '\n<size:' + $TECHN_FONT_SIZE + '>[' + $type + ']</size>'
+!endif
+box "$labelType" $toStereos("boundary", $boundaryTags)
+!endprocedure
+
+!procedure Boundary_End()
+end box
+!endprocedure
+
+!unquoted procedure Enterprise_Boundary($alias, $label, $tags="", $link="")
+  !if ($tags != "")
+    !$allTags = $tags + '+enterprise'
+  !else
+    !$allTags = 'enterprise'
+  !endif
+  ' $type defined via $tag style
+  Boundary($alias, $label, "", $allTags, $link)
+!endprocedure
+
+!unquoted procedure System_Boundary($alias, $label, $tags="", $link="")
+  !if ($tags != "")
+    !$allTags = $tags + '+system'
+  !else
+    !$allTags = 'system'
+  !endif
+  ' $type defined via $tag style
+  Boundary($alias, $label, "", $allTags, $link)
+!endprocedure
+
+!unquoted procedure Container_Boundary($alias, $label, $tags="", $link="")
+  !if ($tags != "")
+    !$allTags = $tags + '+container'
+  !else
+    !$allTags = 'container'
+  !endif
+  ' $type defined via $tag style
+  Boundary($alias, $label, "", $allTags, $link)
+!endprocedure
+
+' Relationship (redefinition)
+' ##################################
+
+' only Rel is supported in sequence diagram
+
+' first Rel() supports the $index and $rel argument too; second Rel() overwrites C4.puml definition
+' don't add empty lines in procedure otherwise & calls are not working anymore '& a -> b: call' are not working anymore
+!unquoted procedure Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="", $index="", $rel="")
+  !if ($show_index == %true())
+    !$pre = $getPrefix($index)
+  !else
+    !$pre = ""
+  !endif
+  !if ($rel == "")
+    !$rel = "->"
+  !endif
+$getRel($rel, $from, $to, $pre + $label, $techn, $descr, $sprite, $tags, $link)
+!endprocedure
+!unquoted procedure Rel($from, $to, $label, $techn="", $descr="", $sprite="", $tags="", $link="")
+Rel($from, $to, $label, $techn, $descr, $sprite, $tags, $link, "", "")
+!endprocedure
diff --git a/C4/INFO b/C4/INFO
index 49e3c220..3553424d 100644
--- a/C4/INFO
+++ b/C4/INFO
@@ -1,2 +1,2 @@
-VERSION=2.7.0
+VERSION=2.8.0
 SOURCE=https://github.com/plantuml-stdlib/C4-PlantUML