B D Finch (asker) Mar 22, 2009:

Main data Thanks Bourth. I simply needed to know what the most generally used wording would be among engineers, i.e. principle/main/key data, so that an engineer looking at the computer screen would not have any hesitation about what data to input and so that s/he would find the expression used not just clear, but the one they would use every day. If "main" sounds good to you and Comunican, that is good enough for me.

Bourth (X) Mar 22, 2009:

Main data "Primary data" does have a specific meaning in data terms, but in your case I imagine not only that the fact that it's for a computer program is pretty much irrelevant but also that it's not actually "primary data", simply the "most important", "key", "most relevant", etc. data for the task at hand.