Thread:Project:Support desk/ START/reply

It was first added as a kind of i18n hack way back in 2003 in, and ignominiously removed a few months later in. It kept receiving new translations for 4 years before someone finally noticed that it was unused and removed it in. Apparently the purpose of __START__ was to allow comments to precede the content of i18n messages, or some such thing. It never would have worked on content pages, since it was never hooked up to the wikitext parser.

If you have a copy of the MediaWiki git repository on your computer, you can use the search functionalities in the  tool to conduct this kind of archaeology. This is how I found all this information out. Very interesting stuff back there in the dim and dusty past...