Lumerical forum supports subset of Markdown, BBCode and HTML formatting, but it is certainly limited. To provide a complete answer, I will quote from the Discourse forum:
There’s three things to consider.
What Markdown is allowed?
What BBCode is allowed?
What HTML is allowed?
All 3 can be mixed and merged to some extent.
Simple: the Markdown implementation is very close to the standard.
We support a subset of “common” BBCode.
> [ul][li]option one[/li][/ul]
> Custom BBCode specific to Discourse, needed for functions that don't fit into Markdown, but do fit into BBCode.
> [spoiler]it's a sled[/spoiler]
> [quote="eviltrout, post:1, topic:2"]
Markdown specifies that it works seamlessly with HTML, so we do.
However, we only support a “safe” subset of HTML. I’ll have to dig to find the specifics, but anything common you’d expect to work that isn’t crazy – like:
<script> -- should work.