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I thought you might have solved my problem.
I use a spreadsheet in which I need to store the serial number for the product issued. The cell shows the product and I then inserted the serial number as a comment. This is fine on the main PC but when I am out on the road I am using Documents To Go to read the spreadsheet on the iPad. Unfortunately neither the Comment or the Data Validation method show up.
Do you have any other suggestions that might work?