If html is allowed, there may still be other filters to remove certain potentially harmful characters or commands. For example the word 'javascript' is re-written as 'java script' by the text sanitiser. 
Bad words can also be identified and re-written in the xoops administration section under 
Preferences Main »» Word Censoring Options.
This option also allows admins to filter out objectionable words from any submission on the site
     
    
    
So does this mean "all" HTML instructions will be recognised. I have already had issues with the use of square or angled brackets?
Is there a published list of permitted HTML instructions with their parameters?