[html5] syntax for server-side processing instructions

[Leonardo Boiko]

Hi,

Sorry if this was already discussed; I get confused easily.  I’d like
to author HTML5 in a parsing text editor.  I’d also like to insert
custom server-side non-HTML instructions – like PHP, ERB &c. – without
confusing the parser; ideally, keeping the whole thing a valid,
conformant HTML5 document (so that my hypothetical validating text
editor can point only actual mistakes).  What’s the preferred approach
for that?

Myself, I’d favor XML-style processing instructions.  Say I have a
blog engine called My Stupid Blog.  Then I could do something like
PHP:

    <?msb include('header.html') ?>

However, from a quick search, it appears that HTML5 does not allow PIs
(at least in HTML syntax, and I’d like to use HTML syntax).

Would it be considered bad form if I just used comments?

    <!--msb include('header.html') -->

Or is there some magical elegant idiom I am missing?

-- 
Leonardo Boiko