RE: [PETAL ERROR] cannot tokenize: <dpchrist-xyI/[email protected]>

petal:

Bruno Postle wrote:
> Petal processes stuff inside html comment blocks and outputs the
> result, presumably this is so you can template your comments.
> If you want to create comments that are ignored completely by Petal
> then you need to use this syntax (note the extra question-mark):
>  <!--? petal ignores me -->

Is this Petal-specific?  XHTML?  Google'ing for "<!--?" doesn't seem to work.
Where is this documented?


TIA,

David