Some of that stuff is in Appendix H of the online documentation:
On Jan 27, 2010, at 1:59 PM, Jonathan Rochkind wrote:
> I know I've seen documetnation on the LC site before for since-abandoned
> marc bib tags, like 400. But I can't for the life of me find it now
> navigating around the website or googling. does anyone know where this is?