LISP to search viewport to update titleblock revision

I'm looking for a lisp routine that is capable of searching the content of my view ports for the highest numeric attribute value with a specific tag. For example we have blocks set up with revision numbers. The revision triangles are named rev1-rev10, each has a specific colour, and each is placed next to a revision cloud with the corresponding color via lisp; the lisp allows you to draw the cloud and automatically inserts the revision triangle when the rev cloud closes.

What I would like to do, it get my hands on a lisp routine that would search each viewport and update my title blocks with the appropriate revision number to ensure each page is up to date.

Any ideas?