If vB code is anything like HTML, the left bracket indicates a tag opening. Whatever’s interpreting the vB code may be expecting a vB command to follow. It doesn’t know you meant to use a bracket in a non-vB sense.
But [this] is in italics, as is [this and this]
and [this] is in bold
and [this] is underlined…
and [sub][subscript]?[/sub] Check.
and [sup][superscript]?[/sup] Check.
and [sym][symbol]?[/sym] Check.
Seems that only the url tag is affected by the presence of brackets.
I don’t know about these things but…
in one of my post I did everything right and I could not get the proper link coding, so (confused) I just started adding stuff til it acted right. Don’t remember the post but it (eventually) looked some thing like this: