1 files changed, 40 insertions, 1 deletions
diff --git a/tex/context/base/mkxl/strc-flt.mklx b/tex/context/base/mkxl/strc-flt.mklx
index 2559e897b..94d06fd92 100644
--- a/tex/context/base/mkxl/strc-flt.mklx
+++ b/tex/context/base/mkxl/strc-flt.mklx
@@ -1092,6 +1092,35 @@
 \def\strc_floats_group_index
   {\numexpr\clf_listgroupindex{\currentfloat}{\currentfloatgroup}\relax}
 
+%D A lightweight subnumber feature:
+%D
+%D \starttyping
+%D \startplacefigure [location=none]
+%D   \startsubfloatnumbering
+%D     \startfloatcombination [nx=3]
+%D       \startplacefigure [title=Left]   \externalfigure \stopplacefigure
+%D       \startplacefigure [title=Middle] \externalfigure \stopplacefigure
+%D       \startplacefigure [title=Right]  \externalfigure \stopplacefigure
+%D     \stopfloatcombination
+%D   \stopsubfloatnumbering
+%D \stopplacefigure
+%D \stoptyping
+
+\glet\currentsubfloatcounter\empty
+
+\permanent\protected\def\startsubfloatnumbering
+  {\glet\currentsubfloatcounter\s!unknown}
+
+\permanent\protected\def\stopsubfloatnumbering
+  {\strc_counters_reset_sub\currentsubfloatcounter\plustwo
+   \glet\currentsubfloatcounter\empty}
+
+\defineconversionset[subfloats][number,characters]
+
+\setupcaptions
+ %[figure]
+  [\c!numberconversionset=subfloats]
+
 \def\strc_floats_place_packaged_boxes
   {\expandafter\strc_floats_place_packaged_boxes_indeed\expandafter{\m_strc_floats_saved_userdata}}
 
@@ -1109,7 +1138,17 @@
      \orelse\ifempty\currentfloatgroup
        % independent
        \iftrialtypesetting\strc_counters_save\currentfloatcounter\fi
-       \strc_counters_increment\currentfloatcounter
+       \ifempty\currentsubfloatcounter
+         \strc_counters_increment\currentfloatcounter
+         \strc_counters_reset_sub\currentfloatcounter\plustwo
+       \else
+         \ifcase\strc_counters_raw_sub\currentfloatcounter\plustwo\relax
+           \strc_counters_increment\currentfloatcounter
+           \strc_counters_reset_sub\currentfloatcounter\plustwo
+         \fi
+         \strc_counters_increment_sub\currentfloatcounter\plustwo
+         \glet\currentsubfloatcounter\currentfloatcounter
+       \fi
      \orelse\ifcase\strc_floats_group_index
        % first in group
        \iftrialtypesetting\strc_counters_save\currentfloatcounter\fi