On Sat, 30 Jun 2007 10:30:53 -0700, Jim Thompson
wrote:

I have a specification for an amplifier design that says "0.25%
linearity".

I can't seem to lay my hands on a precise definition of what that
means.

Likewise... How to calculate?

...Jim Thompson

The data converter people have some measures of non-linearity.

See:

http://www.maxim-ic.com/appnotes.cfm...te_number/740/

http://www.maxim-ic.com/appnotes.cfm...te_number/748/

Maybe your customer is thinking of something along these lines.