This procedure is defined in the server but not documented via ad_proc or proc_doc and may be intended as a private interface.
The procedure is defined as:
proc Markdown::convert {markdown} {
set markdown [regsub {\r\n?} $markdown {\n}]
set markdown [::textutil::untabify2 $markdown 4]
set markdown [string trimright $markdown]
# COLLECT REFERENCES
array unset ::Markdown::_references
array set ::Markdown::_references [collect_references markdown]
# PROCESS
return [apply_templates markdown]
}