HP C5100a question

Folks,

Picked up one of these original `photoscanners' at a second-hand
store. Found a third party (e-mail me) driver/software package for
it, and successfully scanned b/w & color negs and slides.

However, in scan print mode, it asks for a `calibration card'
before it will proceed.

Needless to say, I didn't get this card with the scanner.

What is it? Is it common with the HP film scanner line, and
where might I get one - or how to make one?

Any advice appreciated.

Bill

www.nyx.net/~wboas