Had problem on a BBS with brackets used for array references being confused with BBCode tags.

dim a[3]
for i=0 to 3
  rem The open bracket-i-close bracket in the next line is an array reference,
  rem NOT a BBCode italics tag ...
  let a[i]=1
next

Preview of the above looks OK, though.

Here's some italic text for good measure.

More code:

This code contains BBCode [i]italics[/i] tags, but the tags should be ignored 
due to the enclosing [code] tags.

Looks good!