diff --git a/CHANGES.rst b/CHANGES.rst
index 48e819bb..a6c36a64 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -14,8 +14,26 @@ Breaking Change:
   needs to expect this parameter too!
   [MrTango]
 
+Features:
+
+- Add checkbox to reverse output the filters.
+  [jensens]
+
+- Support and Test Plone 6.
+  [jensens]
+
+- Add a module global COLLECTIONISH_TARGETS to c.c.tiles to register other tiles with collections than plone.app.standardtiles.contentlisting.
+  [jensens]
+
 Bug Fixes:
 
+- Not every metadata entry has an index with same name.
+  Ignore if not a pair.
+  [jensens]
+
+- Fix/Workaround for #59 (Int fields in indexes are not working).
+  [jensens]
+
 - Hide uninstall profiles from install view.
   [jensens]
 
@@ -28,6 +46,7 @@ Bug Fixes:
 - Fixed searches for only non-alphanumeric characters causing an exception to be displayed.
   [JeffersonBledsoe]
 
+
 Other:
 
 - Code-Style Black and Isort
diff --git a/base.cfg b/base.cfg
index 89d11bfb..334c38a5 100644
--- a/base.cfg
+++ b/base.cfg
@@ -17,18 +17,6 @@ plone.batching = >=1.1.7
 # plone.app.standardtiles = 2.3.1 # fix https://github.com/plone/plone.app.standardtiles/issues/111
 pycodestyle =
 
-# Robot Testing (see buildout.coredev[5.2]/versions.cfg)
-plone.app.robotframework = 1.5.4
-robotframework = 3.1.2
-robotframework-python3 = 2.9
-robotframework-debuglibrary = 1.2.1
-robotframework-ride = 1.7.4.1
-robotframework-seleniumlibrary = 3.3.1
-robotframework-selenium2library = 3.0.0
-robotframework-selenium2screenshots = 0.8.1
-robotsuite = 2.2.1
-selenium = 3.141.0
-
 [versions:python27]
 # to get codeanalysis working
 build = 0.1
diff --git a/requirements-5.2.x.txt b/requirements-5.2.x.txt
index 9dd163b8..4ad8c835 100644
--- a/requirements-5.2.x.txt
+++ b/requirements-5.2.x.txt
@@ -1 +1 @@
- -r https://dist.plone.org/release/5.2-latest/requirements.txt
+-r https://dist.plone.org/release/5.2-latest/requirements.txt
diff --git a/requirements-6.0.x.txt b/requirements-6.0.x.txt
index 8b0f7dc3..3ae6c36a 100644
--- a/requirements-6.0.x.txt
+++ b/requirements-6.0.x.txt
@@ -1 +1 @@
- -r https://dist.plone.org/release/6.0-latest/requirements.txt
+-r https://dist.plone.org/release/6.0-latest/requirements.txt
diff --git a/src/collective/collectionfilter/baseviews.py b/src/collective/collectionfilter/baseviews.py
index 26e9053a..ff950ee8 100644
--- a/src/collective/collectionfilter/baseviews.py
+++ b/src/collective/collectionfilter/baseviews.py
@@ -130,13 +130,11 @@ class BaseFilterView(BaseView):
     def input_type(self):
         if self.settings.input_type == "links":
             return "link"
-        elif self.settings.filter_type == "single":
+        if self.settings.filter_type == "single":
             if self.settings.input_type == "checkboxes_radiobuttons":
                 return "radio"
-            else:
-                return "dropdown"
-        else:
-            return "checkbox"
+            return "dropdown"
+        return "checkbox"
 
     # results is called twice inside the template in view/available and view/results.  But its expensive so we cache it
     # but just the the lifetime of the view
@@ -152,6 +150,7 @@ def results(self):
             cache_enabled=self.settings.cache_enabled,
             request_params=self.top_request.form or {},
             content_selector=self.settings.content_selector,
+            reverse=self.settings.reverse,
         )
         return results
 
diff --git a/src/collective/collectionfilter/filteritems.py b/src/collective/collectionfilter/filteritems.py
index 78a8bb8a..432c08e7 100644
--- a/src/collective/collectionfilter/filteritems.py
+++ b/src/collective/collectionfilter/filteritems.py
@@ -42,6 +42,7 @@ def _build_url(
 ):
     # Build filter url query
     _urlquery = urlquery.copy()
+
     # Allow deselection
     if filter_value in current_idx_value:
         _urlquery[idx] = [it for it in current_idx_value if it != filter_value]
@@ -105,6 +106,7 @@ def _results_cachekey(
     cache_enabled=True,
     request_params=None,
     content_selector="",
+    reverse=False,
 ):
     if not cache_enabled:
         raise DontCache
@@ -117,6 +119,7 @@ def _results_cachekey(
         view_name,
         request_params,
         content_selector,
+        reverse,
         " ".join(plone.api.user.get_roles()),
         plone.api.portal.get_current_language(),
         str(plone.api.portal.get_tool("portal_catalog").getCounter()),
@@ -135,6 +138,7 @@ def get_filter_items(
     cache_enabled=True,
     request_params=None,
     content_selector="",
+    reverse=False,
 ):
     request_params = request_params or {}
     custom_query = {}  # Additional query to filter the collection
@@ -189,7 +193,7 @@ def get_filter_items(
     # Allow value_blacklist to be callables for runtime-evaluation
     value_blacklist = (
         value_blacklist() if callable(value_blacklist) else value_blacklist
-    )  # noqa
+    )
     # fallback to title sorted values
     sort_key_function = groupby_criteria[group_by].get(
         "sort_key_function", lambda it: it["title"].lower()
@@ -213,6 +217,9 @@ def get_filter_items(
                 or filter_value in value_blacklist
             ):
                 continue
+            if type(filter_value) == int:
+                # if indexed value is an integer, convert to string
+                filter_value = str(filter_value)
             if filter_value in grouped_results:
                 # Add counter, if filter value is already present
                 grouped_results[filter_value]["count"] += 1
@@ -262,6 +269,9 @@ def get_filter_items(
     if callable(sort_key_function):
         grouped_results = sorted(grouped_results, key=sort_key_function)
 
+    if reverse:
+        grouped_results = reversed(grouped_results)
+
     ret += grouped_results
 
     return ret
diff --git a/src/collective/collectionfilter/interfaces.py b/src/collective/collectionfilter/interfaces.py
index 0d3215d5..f33bb343 100644
--- a/src/collective/collectionfilter/interfaces.py
+++ b/src/collective/collectionfilter/interfaces.py
@@ -132,8 +132,18 @@ class ICollectionFilterSchema(ICollectionFilterBaseSchema):
         vocabulary="collective.collectionfilter.InputType",
     )
 
+    reverse = schema.Bool(
+        title=_(u"label_reverse", default=u"Reverse sort filter"),
+        description=_(
+            u"help_reverse",
+            default=u"Reverse the sorting of th list of filter options.",
+        ),
+        default=False,
+        required=False,
+    )
+
     narrow_down = schema.Bool(
-        title=_(u"label_narrow_down", default=u"Narrow down filter options"),  # noqa
+        title=_(u"label_narrow_down", default=u"Narrow down filter options"),
         description=_(
             u"help_narrow_down",
             default=u"Narrow down the filter options when a filter of this group is applied."  # noqa
@@ -145,7 +155,7 @@ class ICollectionFilterSchema(ICollectionFilterBaseSchema):
     )
 
     hide_if_empty = schema.Bool(
-        title=_(u"label_hide_if_empty", default=u"Hide if empty"),  # noqa
+        title=_(u"label_hide_if_empty", default=u"Hide if empty"),
         description=_(
             u"help_hide_if_empty",
             default=u"Don't display if there is 1 or no options without selecting a filter yet.",
diff --git a/src/collective/collectionfilter/portlets/collectionfilter.py b/src/collective/collectionfilter/portlets/collectionfilter.py
index 9301d4d9..38337d08 100644
--- a/src/collective/collectionfilter/portlets/collectionfilter.py
+++ b/src/collective/collectionfilter/portlets/collectionfilter.py
@@ -28,6 +28,7 @@ class Assignment(base.Assignment):
     view_name = None
     content_selector = "#content-core"
     hide_if_empty = False
+    reverse = False
     # list_scaling = None
 
     def __init__(
@@ -43,6 +44,7 @@ def __init__(
         view_name=None,
         content_selector="#content-core",
         hide_if_empty=False,
+        reverse=False,
         # list_scaling=None
     ):
         self.header = header
@@ -56,6 +58,7 @@ def __init__(
         self.view_name = view_name
         self.content_selector = content_selector
         self.hide_if_empty = hide_if_empty
+        self.reverse = reverse
         # self.list_scaling = list_scaling
 
     @property
diff --git a/src/collective/collectionfilter/testing.py b/src/collective/collectionfilter/testing.py
index dc041935..37ff5f17 100644
--- a/src/collective/collectionfilter/testing.py
+++ b/src/collective/collectionfilter/testing.py
@@ -14,6 +14,8 @@
 
 import json
 import os
+import pytz
+import six
 
 
 try:
@@ -77,12 +79,17 @@ def setUpPloneSite(self, portal):
                     }
                 ],
             )
+            if six.PY2:
+                now = datetime.now()
+            else:
+                now = datetime.now(pytz.UTC)
+
             portal.invokeFactory(
                 "Event",
                 id="testevent",
                 title=u"Test Event",
-                start=datetime.now() + timedelta(days=1),
-                end=datetime.now() + timedelta(days=2),
+                start=now + timedelta(days=1),
+                end=now + timedelta(days=2),
                 subject=[u"Süper", u"Evänt"],
                 exclude_from_nav=False,
             )
diff --git a/src/collective/collectionfilter/tests/robot/test_filterportlets.robot b/src/collective/collectionfilter/tests/robot/test_filterportlets.robot
index 431a6e7b..0605083f 100644
--- a/src/collective/collectionfilter/tests/robot/test_filterportlets.robot
+++ b/src/collective/collectionfilter/tests/robot/test_filterportlets.robot
@@ -45,7 +45,7 @@ Scenario: Test Batching
 Scenario: Hide when no options
 
     Given I've got a site with a collection
-      and my collection has a collection filter  author_name  or  checkboxes_dropdowns  Hide if empty
+      and my collection has a collection filter  Creator  or  checkboxes_dropdowns  Hide if empty
      When I'm viewing the collection
      then Should be 3 collection results
      then Should be 0 filter options
diff --git a/src/collective/collectionfilter/tiles/__init__.py b/src/collective/collectionfilter/tiles/__init__.py
index e6e42637..305775d7 100644
--- a/src/collective/collectionfilter/tiles/__init__.py
+++ b/src/collective/collectionfilter/tiles/__init__.py
@@ -15,6 +15,12 @@
 import re
 
 
+# tile names actijg collectionish
+COLLECTIONISH_TARGETS = [
+    "plone.app.standardtiles.contentlisting",
+]
+
+
 class DictDataWrapper(object):
     def __init__(self, data):
         self.data = data
@@ -51,6 +57,8 @@ def reload_url(self):
 
 
 def findall_tiles(context, spec):
+    if not isinstance(spec, list):
+        spec = [spec]
     request = context.REQUEST
     la = ILayoutAware(context)
     layout = (
@@ -62,8 +70,10 @@ def findall_tiles(context, spec):
     )
     if layout is None:
         return []
-    urls = re.findall(r"(@@[\w\.]+/\w+)", layout)
-    urls = [url for url in urls if url.startswith("@@{}".format(spec))]
+    possible_urls = re.findall(r"(@@[\w\.]+/\w+)", layout)
+    urls = []
+    for name in spec:
+        urls += [url for url in possible_urls if url.startswith("@@{}".format(name))]
     # TODO: maybe better to get tile data? using ITileDataManager(id)?
     our_tile = request.response.headers.get("x-tile-url")
     tiles = [context.unrestrictedTraverse(str(url)) for url in urls]
@@ -107,10 +117,10 @@ def selectContent(self, selector=None):
         if selector is None:
             selector = ""
         self.tile = None
-        tiles = findall_tiles(self.context, "plone.app.standardtiles.contentlisting")
+        tiles = findall_tiles(self.context, COLLECTIONISH_TARGETS)
         for tile in tiles:
             tile.update()
-            tile_classes = tile.tile_class.split() + [""]
+            tile_classes = getattr(tile, "tile_class", "").split() + [""]
             # First tile that matches all the selector classes
             if all([_class in tile_classes for _class in selector.split(".")]):
                 self.tile = tile
@@ -121,25 +131,22 @@ def selectContent(self, selector=None):
             self.tile = tile
         if self.tile is not None or self.collection is not None:
             return self
-        else:
-            return None
 
     @property
     def sort_reversed(self):
         if self.tile is not None:
             return self.sort_order == "reverse"
-        else:
-            return self.collection.sort_reversed
+        return self.collection.sort_reversed
 
     @property
     def content_selector(self):
-        """will return None if no tile or colleciton found"""
+        """will return None if no tile or collection found"""
         if self.collection is None:
-            return None
-        elif self.tile is None:
+            return
+        if self.tile is None:
             return super(CollectionishLayout, self).content_selector
         classes = ["contentlisting-tile"]
-        if self.tile.tile_class:
+        if getattr(self.tile, "tile_class", ""):
             classes += self.tile.tile_class.split()
         return "." + ".".join(classes)
 
diff --git a/src/collective/collectionfilter/vocabularies.py b/src/collective/collectionfilter/vocabularies.py
index 84fcce34..964e97cd 100644
--- a/src/collective/collectionfilter/vocabularies.py
+++ b/src/collective/collectionfilter/vocabularies.py
@@ -26,6 +26,7 @@
 # Use this EMPTY_MARKER for your custom indexer to index empty criterions.
 EMPTY_MARKER = "__EMPTY__"
 TEXT_IDX = "SearchableText"
+INTEGER_IDXS = []
 GEOLOC_IDX = [
     "latitude",
     "longitude",
@@ -56,9 +57,16 @@
     "start",
     "sync_uid",
     "total_comments",
+    "TranslationGroup",
 ] + GEOLOC_IDX  # latitude/longitude is handled as a range filter ... see query.py  # noqa
 DEFAULT_FILTER_TYPE = "single"
 LIST_SCALING = ["No Scaling", "Linear", "Logarithmic"]
+TRUTHY = [
+    safe_encode("true"),
+    safe_encode("1"),
+    safe_encode("t"),
+    safe_encode("yes"),
+]
 
 
 def translate_value(value, *args, **kwargs):
@@ -71,30 +79,26 @@ def translate_messagefactory(value, *args, **kwargs):
 
 def make_bool(value):
     """Transform into a boolean value."""
-    truthy = [
-        safe_encode("true"),
-        safe_encode("1"),
-        safe_encode("t"),
-        safe_encode("yes"),
-    ]
+
     if value is None:
         return
     if isinstance(value, bool):
         return value
-    value = safe_encode(value)
-    value = value.lower()
-    if value in truthy:
-        return True
-    else:
-        return False
+    value = safe_encode(value).lower()
+    return value in TRUTHY
+
+
+def make_int(value):
+    if isinstance(value, (list, tuple)):
+        return [int(val) for val in value]
+    return int(value)
 
 
 def yes_no(value):
     """Return i18n message for a value."""
     if value:
         return _(u"Yes")
-    else:
-        return _(u"No")
+    return _(u"No")
 
 
 def get_yes_no_title(item, *args, **kwargs):
@@ -143,11 +147,13 @@ def groupby(self):
         # get catalog metadata schema, but filter out items which cannot be
         # used for grouping
         metadata = [it for it in cat.schema() if it not in GROUPBY_BLACKLIST]
-
         for it in metadata:
+            if it not in cat.indexes():
+                # collectionfilter needs both, metadata and index entries.
+                continue
+            idx = cat._catalog.indexes.get(it)
             index_modifier = None
             display_modifier = translate_value  # Allow to translate in this package domain per default.  # noqa
-            idx = cat._catalog.indexes.get(it)
             if six.PY2 and getattr(idx, "meta_type", None) == "KeywordIndex":
                 # in Py2 KeywordIndex accepts only utf-8 encoded values.
                 index_modifier = safe_encode
@@ -156,6 +162,9 @@ def groupby(self):
                 index_modifier = make_bool
                 display_modifier = get_yes_no_title
 
+            if idx.getId() in INTEGER_IDXS:
+                index_modifier = make_int
+
             # for portal_type or Type we have some special sauce as we need to translate via fti.i18n_domain.  # noqa
             if it == "portal_type":
                 display_modifier = translate_portal_type
@@ -187,7 +196,7 @@ def groupby(self, value):
 def GroupByCriteriaVocabulary(context):
     """Collection filter group by criteria."""
     groupby = getUtility(IGroupByCriteria).groupby
-    items = [SimpleTerm(title=_(it), value=it) for it in groupby.keys()]
+    items = [SimpleTerm(value=it, token=str(it), title=_(it)) for it in groupby.keys()]
     return SimpleVocabulary(items)
 
 
@@ -209,10 +218,10 @@ def InputTypeVocabulary(context):
         SimpleTerm(
             title=_("inputtype_checkboxes_radiobuttons"),
             value="checkboxes_radiobuttons",
-        ),  # noqa
+        ),
         SimpleTerm(
             title=_("inputtype_checkboxes_dropdowns"), value="checkboxes_dropdowns"
-        ),  # noqa
+        ),
     ]
     return SimpleVocabulary(items)
 
@@ -231,5 +240,5 @@ def SortOnIndexesVocabulary(context):
     sortable_indexes = reader().get("sortable_indexes")
     items = [
         SimpleTerm(title=_(v["title"]), value=k) for k, v in sortable_indexes.items()
-    ]  # noqa
+    ]
     return SimpleVocabulary(items)
diff --git a/test-5.2.x.cfg b/test-5.2.x.cfg
index dd888675..dd44bfa1 100644
--- a/test-5.2.x.cfg
+++ b/test-5.2.x.cfg
@@ -18,5 +18,17 @@ test-eggs =
 extensions +=
     flake8-black
 
+[versions]
+plone.app.robotframework = 1.5.4
+robotframework = 3.1.2
+robotframework-python3 = 2.9
+robotframework-debuglibrary = 1.2.1
+robotframework-ride = 1.7.4.1
+robotframework-seleniumlibrary = 3.3.1
+robotframework-selenium2library = 3.0.0
+robotframework-selenium2screenshots = 0.8.1
+robotsuite = 2.2.1
+selenium = 3.141.0
+
 [versions:python3]
 coverage = >=3.7