I am a member of The PostgreSQL Foundation
for automatic mail filtering.
They use standard HTML tags, and may be considered Lynx-friendly which involves only non-exclusionary enhancements.
Virtually all of my web pages are composed using SGML-Tools, which uses SGML (Standard Generalized Markup Language) with the DocBook DTD, along with Norm Walsh's DSSSL -based Modular DocBook Stylesheets, that use Jade to generate HTML output. This production process, managed using GNU Make (so that all I need do to get most of this stuff to happen is to type make), guarantees that the pages that you see contain valid HTML.
I do have some ECMAscript inclusions for some Google sales-ish functionality; that doesn't adversely affect users of browsers that do not support it.
As a result of Linux, my LAN at home is entirely free of Microsoft products, and as a result is General Protection Fault-free, and happily hosts many things such as PostgreSQL, news, time, and caching proxy servers, numerous language compilers, document processing using TeX, LaTeX...
I've registered at the Linux Counter
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