AppKitTOC.html is the AppKit table of contents index file.
The online version is:
http://developer.apple.com/techpubs/macosx/Cocoa/Reference/ApplicationKit/ObjC_classic/index.html
Which, as you can see, is no longer named AppKitTOC at all. Of course, it has some very nice new cross-indexing bits that the current dev-tools version doesn’t have.
The version on your hard drive is at:
file:///System/Library/Frameworks/AppKit.framework/Versions/C/Resources/English.lproj/Documentation/Reference/ObjC_classic/AppKitTOC.html
The legend lives on!