diff --git a/experiments/exp-bdc-problem-harfmode.tex b/experiments/exp-bdc-problem-harfmode.tex
new file mode 100644
index 00000000..24238f80
--- /dev/null
+++ b/experiments/exp-bdc-problem-harfmode.tex
@@ -0,0 +1,26 @@
+\documentclass[12pt]{article}
+\usepackage{tagpdf}
+\tagpdfsetup{activate-all,uncompress,tagunmarked=false}
+\directlua{
+  local cbs = luatexbase.callback_descriptions'glyph_info'
+  local desc = cbs[1]
+  assert(desc == "Harf glyph_info callback" and nil == next(cbs, 1))
+  local cb = luatexbase.remove_from_callback('glyph_info', desc)
+  luatexbase.add_to_callback('glyph_info', function(n)
+    return string.format('"\csstring\%s" \csstring\%04X \csstring\%+i:\csstring\%+i', cb(n), n.char, n.xoffset, n.yoffset)
+  end, 'Harf glyph_info callback -- testing variant')
+}
+\usepackage{l3pdf}
+\ExplSyntaxOn
+\pdf_uncompress:
+\ExplSyntaxOff
+\usepackage{fontspec}
+
+\begin{document}
+\tagstructbegin{tag=Document}
+\tagmcbegin{tag=P}
+\fontspec{NotoSerifMyanmar-Regular.ttf}[RawFeature={mode=harf;script=mymr;}]
+မ္မတီခေါင်းလောင်းကြီ
+\par\tagmcend\tagstructend\newpage
+
+\end{document}
\ No newline at end of file