Ever wondered why SharePoint “lists web service” (i.e., lists.asmx) lives in an interesting address of http://mossserver/sites/somesite/_vti_bin/lists.asmx ?
This is actually not the only place where you can see the magic _vti_something. I remember myself deleting such directories from “wwwroot” quite often back in the days “everyone” used MS FrontPage. FrontPage used to create the folders “_vti_bin”, “_vti_cnf” on your computer locally as you developed a website .. and also on the server, if you used “Frontpage Extensions” for publishing. The _bin folder would normally contain executables required for FP server components (as far as I understand, something like cgi_bin).
So, even though FP is announced dead, guys from the SharePoint team apparently like the idea of puting executables in the _vti_bin folder which was used by FrontPage Extensions.
Anyway, the question is, what does the acronym “VTI” mean. Apparently, Microsoft did not develop MS FrontPage from scratch, they acquired “Vermeer Technologies Inc”. Thus the name of “bin” folder in FrontPage. Thus the URL for lists.asmx in SharePoint.