labeling worksheets

Hi all,

I wrote this interpolation add-in. It basicly performs two tasks:

1) Import data from a text file to a newly added worksheet. The data consists of numerical data from graphs, all sampled at different points.

2) recalculate the imported data (interpolation at fixed points), and write new data to another worksheet.

Now I want to be able to distinguish between the imported sheets, the calculated sheets, and the sheets that were not added by the add-in.

Any ideas on how to do this? I thought of programmatically adding a module to the sheets with just 1 boolean variable: imported

Then a can have three situations:
1) imported = true: The sheet contains imported data
2) imported = false: The sheet contains calculated data
3) when the variable 'imported' does not exist, the sheet was not added by the add-in.

Is this approach feasable? How would I code this? Any other ideas?

Any reaction is greatly appreciated...