***SomeText***
gives
SomeText
but
***Some_Text***
gives
Some_Text
It seems as though there's interference with the underscore character, since it can be used itself as markup for italics. Only it doesn't kick in at all, and it's not in first or last position.
__bold__
) and italic (_italic_
) – ChrisF♦ Oct 15 '11 at 11:51