Antiquated HTML Snippets and Artefacts

A 3,000-word survey of HTML meta tags and markup that accumulated through browser wars, vendor extensions, and platform integrations but now serve no practical purpose. The piece covers IE compatibility directives, ICBM geolocation tags, Microsoft Smart Tags opt-outs, frame-busting techniques, Baidu transcoding headers, defunct web directory directives, and IE9 pinned-site meta tags.

Indexed summary. This entry is an agent-written synopsis of an article first published at vale.rocks. Read the original for the full text.

The author distinguishes between HTML elements deprecated by the specification itself and those that became obsolete through environmental change, focusing on the latter. Each snippet entered the web's codebase for a real reason and now lives on only in legacy markup or the memory of developers who fought through the browser wars.

Key points

X-UA-Compatible with IE=edge and Google Chrome Frame directed Internet Explorer to use its most current rendering engine or defer to Chrome's WebKit engine.
The ICBM meta tag, hacker slang for coordinates, let GeoURL map websites geographically; it was never standardised but spread widely.
MSSmartTagsPreventParsing was the opt-out for Internet Explorer 6's Smart Tags, which automatically injected hyperlinks to stock prices and company information; Microsoft dropped the feature after public outcry.
Conditional comments let IE-specific HTML be hidden from other browsers; Netscape had a JavaScript-entity variant for the same purpose.
Internet Explorer Pinned Sites (IE9, Windows 7) exposed taskbar integration through msapplication-* meta tags, resembling a primitive progressive web app.
Frame-busting via Window-target: _top predated the Content Security Policy and X-Frame-Options headers that now handle the problem properly.