Bug overview description.
Starting dtext with uppercase letters, like h4. [sub], makes it not work.

What part(s) of the site page(s) are affected?
Forums and comments I know for a fact but I'm guessing all dtext.

What is the expected behavior?
Non-case-sensitive.

What actual behavior is given instead?

H4.there is text under this title
Text

[Sub]this is written in 'sub'[/sub]

Results in:

there is text under this title

Text

_{this is written in 'sub'}

Time of incident (if applicable).
N/a

Can you reproduce the bug every time?
Yes.

What steps did you take to replicate this bug?
See above.

Errors or other messages returned (if any).
N/a