Doug McIlroy is still alive, so if anyone knows him they can ask him. There was just another piece on HN the other day where he clarified some internal data structure he used in the spell(1) command.

> the problem of indexing and finding relevant information is tougher today than ever before, even on one's own hard disk, let alone the WWW.

Ironically, it's harder on your own drive than on the Web, courtesy Google, Bing, Yandex, You.com and others.

Command+Space (Spolight search) on the Mac? "locate", "man -k", "whereis" on Linux? All feels 1960-ish to me...