Windows Cached Credentials/Security Verifier

[k41zen at live.co.uk (k41zen)]

So the business wants users to be able to log onto laptops using  
cached domain credentials whilst they are offline.

The supplier has limited the number of cached credentials/security  
verifier's available to 5.

My question is how is the "security verifier's table" (for want of a  
better description) managed? If it is full and as a 6th unique account  
I logon connected to the domain, which entry gets overwritten? Does it  
overwrite the oldest verifier that hasn't been logged on recently?  
Does it overwrite the first one in the table?

I'm finding little info on the algorithm used (if any).

Grateful for any insight.