Max,
What sort of Comments are you looking for?
In Entry & Approval when you submit your data entry for approval a Comments box will appear that allows you to submit a comment to the Approver about the data that you have entered e.g. explaining why a figure which might appear wrong is in fact correct. This will appear in the Approvers notification and can be seen by looking at the Approval log by selecting the metric set in question. Equally if an Approver rejects data they get a Comments box to explain why they are rejecting the data.
Regards
Colin Cooper