As 's syntax check is quite small and clusmy, take look at one of the following sources:

• SGMLS (Amiga port, source included; available via aminet:dev/lang/sgmls.lha)
• , a Perl-script that is even more cryptic to configure than
• HalSoft's validation service

And some pages that have been quite useful during the development of :

• The only human readable HTML-reference I've found so far.
• A W3-FAQ that covers even the Amiga.