*for<em>and**for<strong>- definitely- Leading
#for<h1>,<h2>etc. - probably _and__- definitely not, conflict with naked temp variables- link syntax, e.g.
[Link text](Passage name)- maybe - Leading
>for blockquotes - probably not - Leading
*or-or numbers for lists - maybe ---or___or***for<hr>- probably for---and***, maybe for___- code blocks (indented or fenced) - probably not
- setext headings (one or more lines of text followed by
---or===) - probably not