diff --git a/1904/1900.biff5 b/1904/1900.biff5
new file mode 100644
index 0000000..a926e26
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diff --git a/1904/1900.ods b/1904/1900.ods
new file mode 100644
index 0000000..6901b57
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diff --git a/1904/1900.slk b/1904/1900.slk
new file mode 100644
index 0000000..4a2d5d5
--- /dev/null
+++ b/1904/1900.slk
@@ -0,0 +1,93 @@
+ID;PWXL;N;E
+P;PGeneral
+P;P0
+P;P0.00
+P;P#,##0
+P;P#,##0.00
+P;P#,##0_);;\(#,##0\)
+P;P#,##0_);;[Red]\(#,##0\)
+P;P#,##0.00_);;\(#,##0.00\)
+P;P#,##0.00_);;[Red]\(#,##0.00\)
+P;P"$"#,##0_);;\("$"#,##0\)
+P;P"$"#,##0_);;[Red]\("$"#,##0\)
+P;P"$"#,##0.00_);;\("$"#,##0.00\)
+P;P"$"#,##0.00_);;[Red]\("$"#,##0.00\)
+P;P0%
+P;P0.00%
+P;P0.00E+00
+P;P##0.0E+0
+P;P#\ ?/?
+P;P#\ ??/??
+P;Pm/d/yy
+P;Pd\-mmm\-yy
+P;Pd\-mmm
+P;Pmmm\-yy
+P;Ph:mm\ AM/PM
+P;Ph:mm:ss\ AM/PM
+P;Ph:mm
+P;Ph:mm:ss
+P;Pm/d/yy\ h:mm
+P;Pmm:ss
+P;Pmm:ss.0
+P;P@
+P;P[h]:mm:ss
+P;P_("$"* #,##0_);;_("$"* \(#,##0\);;_("$"* "-"_);;_(@_)
+P;P_(* #,##0_);;_(* \(#,##0\);;_(* "-"_);;_(@_)
+P;P_("$"* #,##0.00_);;_("$"* \(#,##0.00\);;_("$"* "-"??_);;_(@_)
+P;P_(* #,##0.00_);;_(* \(#,##0.00\);;_(* "-"??_);;_(@_)
+P;P[$-409]dddd\,\ mmmm\ d\,\ yyyy
+P;Pyyyy\-mm\-dd;;@
+P;P"Yes";;"Yes";;"No"
+P;P"True";;"True";;"False"
+P;P"On";;"On";;"Off"
+P;P[$NCU-2]\ #,##0.00_);;[Red]\([$NCU-2]\ #,##0.00\)
+P;FCalibri;M240;L9
+P;FCalibri;M240;L9
+P;FCalibri;M240;L9
+P;FCalibri;M240;L9
+P;ECalibri;M240;L9
+P;ECalibri Light;M360;L55
+P;ECalibri;M300;SB;L55
+P;ECalibri;M260;SB;L55
+P;ECalibri;M220;SB;L55
+P;ECalibri;M240;L18
+P;ECalibri;M240;L21
+P;ECalibri;M240;L61
+P;ECalibri;M240;L63
+P;ECalibri;M240;SB;L64
+P;ECalibri;M240;SB;L53
+P;ECalibri;M240;L53
+P;ECalibri;M240;SB;L10
+P;ECalibri;M240;L11
+P;ECalibri;M240;SI;L24
+P;ECalibri;M240;SB;L9
+P;ECalibri;M240;L10
+F;P0;DG0G10;M320
+B;Y5;X4;D0 0 4 3
+O;L;D;B;V0;K47;G100 0.001
+C;Y1;X1;K1
+F;P37;FG0G;X2
+C;K1
+C;X3;K"1900-01-01";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1900-01-01";ET(RC[-1])
+C;Y2;X1;K11
+F;P37;FG0G;X2
+C;K11
+C;X3;K"1900-01-11";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1900-01-11";ET(RC[-1])
+C;Y3;X1;K111
+F;P37;FG0G;X2
+C;K111
+C;X3;K"1900-04-20";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1900-04-20";ET(RC[-1])
+C;Y4;X1;K1111
+F;P37;FG0G;X2
+C;K1111
+C;X3;K"1903-01-15";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1903-01-15";ET(RC[-1])
+C;Y5;X1;K11111
+F;P37;FG0G;X2
+C;K11111
+C;X3;K"1930-06-02";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1930-06-02";ET(RC[-1])
+E
diff --git a/1904/1900.xls b/1904/1900.xls
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index 0000000..a8b25b5
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diff --git a/1904/1900.xlsb b/1904/1900.xlsb
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index 0000000..3a22f20
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diff --git a/1904/1900.xlsx b/1904/1900.xlsx
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index 0000000..8072e7d
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diff --git a/1904/1900.xml b/1904/1900.xml
new file mode 100644
index 0000000..793e69f
--- /dev/null
+++ b/1904/1900.xml
@@ -0,0 +1,91 @@
+<?xml version="1.0"?>
+<?mso-application progid="Excel.Sheet"?>
+<Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet"
+ xmlns:o="urn:schemas-microsoft-com:office:office"
+ xmlns:x="urn:schemas-microsoft-com:office:excel"
+ xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet"
+ xmlns:html="http://www.w3.org/TR/REC-html40">
+ <DocumentProperties xmlns="urn:schemas-microsoft-com:office:office">
+  <Author>Sheet</Author>
+  <LastAuthor>Sheet</LastAuthor>
+  <Created>2022-06-03T00:11:34Z</Created>
+  <LastSaved>2022-06-03T00:14:19Z</LastSaved>
+  <Version>16.00</Version>
+ </DocumentProperties>
+ <OfficeDocumentSettings xmlns="urn:schemas-microsoft-com:office:office">
+  <AllowPNG/>
+ </OfficeDocumentSettings>
+ <ExcelWorkbook xmlns="urn:schemas-microsoft-com:office:excel">
+  <WindowHeight>17440</WindowHeight>
+  <WindowWidth>28040</WindowWidth>
+  <WindowTopX>5180</WindowTopX>
+  <WindowTopY>3000</WindowTopY>
+  <DoNotCalculateBeforeSave/>
+  <ProtectStructure>False</ProtectStructure>
+  <ProtectWindows>False</ProtectWindows>
+ </ExcelWorkbook>
+ <Styles>
+  <Style ss:ID="Default" ss:Name="Normal">
+   <Alignment ss:Vertical="Bottom"/>
+   <Borders/>
+   <Font ss:FontName="Calibri" x:Family="Swiss" ss:Size="12" ss:Color="#000000"/>
+   <Interior/>
+   <NumberFormat/>
+   <Protection/>
+  </Style>
+  <Style ss:ID="s62">
+   <NumberFormat ss:Format="yyyy\-mm\-dd;@"/>
+  </Style>
+ </Styles>
+ <Worksheet ss:Name="Sheet1">
+  <Table ss:ExpandedColumnCount="4" ss:ExpandedRowCount="5" x:FullColumns="1"
+   x:FullRows="1" ss:DefaultColumnWidth="65" ss:DefaultRowHeight="16">
+   <Row>
+    <Cell><Data ss:Type="Number">1</Data></Cell>
+    <Cell ss:StyleID="s62"><Data ss:Type="DateTime">1900-01-01T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1900-01-01</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1900-01-01</Data></Cell>
+   </Row>
+   <Row>
+    <Cell><Data ss:Type="Number">11</Data></Cell>
+    <Cell ss:StyleID="s62"><Data ss:Type="DateTime">1900-01-11T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1900-01-11</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1900-01-11</Data></Cell>
+   </Row>
+   <Row>
+    <Cell><Data ss:Type="Number">111</Data></Cell>
+    <Cell ss:StyleID="s62"><Data ss:Type="DateTime">1900-04-20T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1900-04-20</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1900-04-20</Data></Cell>
+   </Row>
+   <Row>
+    <Cell><Data ss:Type="Number">1111</Data></Cell>
+    <Cell ss:StyleID="s62"><Data ss:Type="DateTime">1903-01-15T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1903-01-15</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1903-01-15</Data></Cell>
+   </Row>
+   <Row>
+    <Cell><Data ss:Type="Number">11111</Data></Cell>
+    <Cell ss:StyleID="s62"><Data ss:Type="DateTime">1930-06-02T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1930-06-02</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1930-06-02</Data></Cell>
+   </Row>
+  </Table>
+  <WorksheetOptions xmlns="urn:schemas-microsoft-com:office:excel">
+   <PageSetup>
+    <Header x:Margin="0.3"/>
+    <Footer x:Margin="0.3"/>
+    <PageMargins x:Bottom="0.75" x:Left="0.7" x:Right="0.7" x:Top="0.75"/>
+   </PageSetup>
+   <Selected/>
+   <Panes>
+    <Pane>
+     <Number>3</Number>
+     <ActiveCol>3</ActiveCol>
+    </Pane>
+   </Panes>
+   <ProtectObjects>False</ProtectObjects>
+   <ProtectScenarios>False</ProtectScenarios>
+  </WorksheetOptions>
+ </Worksheet>
+</Workbook>
diff --git a/1904/1904.biff5 b/1904/1904.biff5
new file mode 100644
index 0000000..f2d1713
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diff --git a/1904/1904.ods b/1904/1904.ods
new file mode 100644
index 0000000..8679226
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diff --git a/1904/1904.slk b/1904/1904.slk
new file mode 100644
index 0000000..6da2952
--- /dev/null
+++ b/1904/1904.slk
@@ -0,0 +1,92 @@
+ID;PWXL;N;E
+P;PGeneral
+P;P0
+P;P0.00
+P;P#,##0
+P;P#,##0.00
+P;P#,##0_);;\(#,##0\)
+P;P#,##0_);;[Red]\(#,##0\)
+P;P#,##0.00_);;\(#,##0.00\)
+P;P#,##0.00_);;[Red]\(#,##0.00\)
+P;P"$"#,##0_);;\("$"#,##0\)
+P;P"$"#,##0_);;[Red]\("$"#,##0\)
+P;P"$"#,##0.00_);;\("$"#,##0.00\)
+P;P"$"#,##0.00_);;[Red]\("$"#,##0.00\)
+P;P0%
+P;P0.00%
+P;P0.00E+00
+P;P##0.0E+0
+P;P#\ ?/?
+P;P#\ ??/??
+P;Pm/d/yy
+P;Pd\-mmm\-yy
+P;Pd\-mmm
+P;Pmmm\-yy
+P;Ph:mm\ AM/PM
+P;Ph:mm:ss\ AM/PM
+P;Ph:mm
+P;Ph:mm:ss
+P;Pm/d/yy\ h:mm
+P;Pmm:ss
+P;Pmm:ss.0
+P;P@
+P;P[h]:mm:ss
+P;P_("$"* #,##0_);;_("$"* \(#,##0\);;_("$"* "-"_);;_(@_)
+P;P_(* #,##0_);;_(* \(#,##0\);;_(* "-"_);;_(@_)
+P;P_("$"* #,##0.00_);;_("$"* \(#,##0.00\);;_("$"* "-"??_);;_(@_)
+P;P_(* #,##0.00_);;_(* \(#,##0.00\);;_(* "-"??_);;_(@_)
+P;Pyyyy\-mm\-dd;;@
+P;P"Yes";;"Yes";;"No"
+P;P"True";;"True";;"False"
+P;P"On";;"On";;"Off"
+P;P[$NCU-2]\ #,##0.00_);;[Red]\([$NCU-2]\ #,##0.00\)
+P;FCalibri;M240;L9
+P;FCalibri;M240;L9
+P;FCalibri;M240;L9
+P;FCalibri;M240;L9
+P;ECalibri;M240;L9
+P;ECalibri Light;M360;L55
+P;ECalibri;M300;SB;L55
+P;ECalibri;M260;SB;L55
+P;ECalibri;M220;SB;L55
+P;ECalibri;M240;L18
+P;ECalibri;M240;L21
+P;ECalibri;M240;L61
+P;ECalibri;M240;L63
+P;ECalibri;M240;SB;L64
+P;ECalibri;M240;SB;L53
+P;ECalibri;M240;L53
+P;ECalibri;M240;SB;L10
+P;ECalibri;M240;L11
+P;ECalibri;M240;SI;L24
+P;ECalibri;M240;SB;L9
+P;ECalibri;M240;L10
+F;P0;DG0G10;M320
+B;Y5;X4;D0 0 4 3
+O;L;D;B;V4;K47;G100 0.001
+C;Y1;X1;K1
+F;P36;FG0G;X2
+C;K1
+C;X3;K"1904-01-02";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1904-01-02";ET(RC[-1])
+C;Y2;X1;K11
+F;P36;FG0G;X2
+C;K11
+C;X3;K"1904-01-12";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1904-01-12";ET(RC[-1])
+C;Y3;X1;K111
+F;P36;FG0G;X2
+C;K111
+C;X3;K"1904-04-21";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1904-04-21";ET(RC[-1])
+C;Y4;X1;K1111
+F;P36;FG0G;X2
+C;K1111
+C;X3;K"1907-01-16";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1907-01-16";ET(RC[-1])
+C;Y5;X1;K11111
+F;P36;FG0G;X2
+C;K11111
+C;X3;K"1934-06-03";ETEXT(RC[-1],"YYYY-MM-DD")
+C;X4;K"1934-06-03";ET(RC[-1])
+E
diff --git a/1904/1904.xls b/1904/1904.xls
new file mode 100644
index 0000000..b4a2972
Binary files /dev/null and b/1904/1904.xls differ
diff --git a/1904/1904.xlsb b/1904/1904.xlsb
new file mode 100644
index 0000000..6ddb666
Binary files /dev/null and b/1904/1904.xlsb differ
diff --git a/1904/1904.xlsx b/1904/1904.xlsx
new file mode 100644
index 0000000..6655742
Binary files /dev/null and b/1904/1904.xlsx differ
diff --git a/1904/1904.xml b/1904/1904.xml
new file mode 100644
index 0000000..5da9636
--- /dev/null
+++ b/1904/1904.xml
@@ -0,0 +1,93 @@
+<?xml version="1.0"?>
+<?mso-application progid="Excel.Sheet"?>
+<Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet"
+ xmlns:o="urn:schemas-microsoft-com:office:office"
+ xmlns:x="urn:schemas-microsoft-com:office:excel"
+ xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet"
+ xmlns:html="http://www.w3.org/TR/REC-html40">
+ <DocumentProperties xmlns="urn:schemas-microsoft-com:office:office">
+  <Author>Sheet</Author>
+  <LastAuthor>Sheet</LastAuthor>
+  <Created>2022-06-03T00:11:34Z</Created>
+  <LastSaved>2022-06-03T00:36:09Z</LastSaved>
+  <Version>16.00</Version>
+ </DocumentProperties>
+ <OfficeDocumentSettings xmlns="urn:schemas-microsoft-com:office:office">
+  <AllowPNG/>
+ </OfficeDocumentSettings>
+ <ExcelWorkbook xmlns="urn:schemas-microsoft-com:office:excel">
+  <WindowHeight>17440</WindowHeight>
+  <WindowWidth>28040</WindowWidth>
+  <WindowTopX>5180</WindowTopX>
+  <WindowTopY>3000</WindowTopY>
+  <DoNotCalculateBeforeSave/>
+  <Date1904/>
+  <ProtectStructure>False</ProtectStructure>
+  <ProtectWindows>False</ProtectWindows>
+ </ExcelWorkbook>
+ <Styles>
+  <Style ss:ID="Default" ss:Name="Normal">
+   <Alignment ss:Vertical="Bottom"/>
+   <Borders/>
+   <Font ss:FontName="Calibri" x:Family="Swiss" ss:Size="12" ss:Color="#000000"/>
+   <Interior/>
+   <NumberFormat/>
+   <Protection/>
+  </Style>
+  <Style ss:ID="s16">
+   <NumberFormat ss:Format="yyyy\-mm\-dd;@"/>
+  </Style>
+ </Styles>
+ <Worksheet ss:Name="Sheet1">
+  <Table ss:ExpandedColumnCount="4" ss:ExpandedRowCount="5" x:FullColumns="1"
+   x:FullRows="1" ss:DefaultColumnWidth="65" ss:DefaultRowHeight="16">
+   <Row>
+    <Cell><Data ss:Type="Number">1</Data></Cell>
+    <Cell ss:StyleID="s16"><Data ss:Type="DateTime">1904-01-02T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1904-01-02</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1904-01-02</Data></Cell>
+   </Row>
+   <Row>
+    <Cell><Data ss:Type="Number">11</Data></Cell>
+    <Cell ss:StyleID="s16"><Data ss:Type="DateTime">1904-01-12T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1904-01-12</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1904-01-12</Data></Cell>
+   </Row>
+   <Row>
+    <Cell><Data ss:Type="Number">111</Data></Cell>
+    <Cell ss:StyleID="s16"><Data ss:Type="DateTime">1904-04-21T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1904-04-21</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1904-04-21</Data></Cell>
+   </Row>
+   <Row>
+    <Cell><Data ss:Type="Number">1111</Data></Cell>
+    <Cell ss:StyleID="s16"><Data ss:Type="DateTime">1907-01-16T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1907-01-16</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1907-01-16</Data></Cell>
+   </Row>
+   <Row>
+    <Cell><Data ss:Type="Number">11111</Data></Cell>
+    <Cell ss:StyleID="s16"><Data ss:Type="DateTime">1934-06-03T00:00:00.000</Data></Cell>
+    <Cell ss:Formula="=TEXT(RC[-1],&quot;YYYY-MM-DD&quot;)"><Data ss:Type="String">1934-06-03</Data></Cell>
+    <Cell ss:Formula="=T(RC[-1])"><Data ss:Type="String">1934-06-03</Data></Cell>
+   </Row>
+  </Table>
+  <WorksheetOptions xmlns="urn:schemas-microsoft-com:office:excel">
+   <PageSetup>
+    <Header x:Margin="0.3"/>
+    <Footer x:Margin="0.3"/>
+    <PageMargins x:Bottom="0.75" x:Left="0.7" x:Right="0.7" x:Top="0.75"/>
+   </PageSetup>
+   <Selected/>
+   <Panes>
+    <Pane>
+     <Number>3</Number>
+     <ActiveRow>8</ActiveRow>
+     <ActiveCol>3</ActiveCol>
+    </Pane>
+   </Panes>
+   <ProtectObjects>False</ProtectObjects>
+   <ProtectScenarios>False</ProtectScenarios>
+  </WorksheetOptions>
+ </Worksheet>
+</Workbook>
diff --git a/README.md b/README.md
index a6d2a98..cce529b 100644
--- a/README.md
+++ b/README.md
@@ -148,6 +148,8 @@ output in various plain-text formats as generated by Excel 2011.
 
 `crlf` tests plaintext and formula newline scenarios
 
+`1904` includes artifacts using 1900 and 1904 date systems
+
 # Getting External Test Files
 
 Note: releases from <https://github.com/sheetjs/test_files/releases> include all