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diff --git a/tex/context/modules/mkiv/s-fonts-features.mkiv b/tex/context/modules/mkiv/s-fonts-features.mkiv
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+%D \module
+%D   [      file=s-fonts-features, % was s-fnt-41, s-fnt-27
+%D        version=2012.11.27, % 2010.02.22
+%D          title=\CONTEXT\ Style File,
+%D       subtitle=Features,
+%D         author=Hans Hagen,
+%D           date=\currentdate,
+%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
+%C
+%C This module is part of the \CONTEXT\ macro||package and is
+%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
+%C details.
+
+\startmodule[fonts-features]
+
+\registerctxluafile{s-fonts-features}{}
+
+\installmodulecommandluasingle \showusedfeatures {moduledata.fonts.features.showused}
+\installmodulecommandluasingle \showallkerns     {moduledata.fonts.features.showallkerns}
+\installmodulecommandluasingle \showbasekerns    {moduledata.fonts.features.showbasekerns}
+
+\def\kernpairheight{\strutheight}
+\def\kernpairdepth {\strutdepth}
+\def\kernpairwidth {\onepoint}
+
+\unexpanded\def\showkernpair#1#2#3% first second kern
+  {\dontleavehmode
+   \hbox \bgroup
+   \scratchdimen#2\scaledpoint
+   \kern\fontcharwd\font#1\relax
+   \ifdim\scratchdimen>\zeropoint
+     \bgroup
+       \darkgreen
+       \vrule width \scratchdimen height \kernpairheight depth \kernpairdepth
+     \egroup
+     \kern-\scratchdimen
+   \else\ifdim\scratchdimen<\zeropoint
+     \kern\scratchdimen
+     \bgroup
+       \darkred
+       \vrule width -\scratchdimen height \kernpairheight depth \kernpairdepth
+     \egroup
+   \else
+     \kern-.5\dimexpr\kernpairwidth\relax
+     \bgroup
+       \darkblue
+       \vrule width \kernpairwidth height \kernpairheight depth \kernpairdepth
+     \egroup
+     \kern-.5\dimexpr\kernpairwidth\relax
+   \fi\fi
+   \kern-\fontcharwd\font#1\relax
+   \char#1\relax
+   \char#3\relax
+   \egroup
+   \space}
+
+\stopmodule
+
+\continueifinputfile{s-fonts-features.mkiv}
+
+\usemodule
+  [art-01]
+
+\starttext
+
+    \showusedfeatures \page
+
+    \definefontfeature[default-base][default][mode=base]
+
+    \start
+        \definedfont[Serif*default-base]
+        \showbasekerns
+        \page
+    \stop
+
+    \start
+        \bf
+        \showallkerns
+        \page
+    \stop
+
+\stoptext