.NET: with respect to AssemblyVersion, what defines binary compatibility?

Question

What changes to a strong-named assembly necessitate a change in AssemblyVersionAttribute? Clearly, changing the public api in a way that could require a client to have to make a

Answer 1

In response to Martijn's bounty:

The best reference on binary compatibility is on the community Wiki.

A definite guide to API-breaking changes in .NET