When responding to an RFP or eTender in PostRFP, there are two places where files may be attached:
With Questions Attachments, only one file may be uploaded per field.
Response Attachments are more flexible. A respondent can upload any number of attachments by clicking the "Attachments" link in the tree menu. However, when using the Response Attachment upload form it is compulsory to write a description so that the buyer knows what to do with the attachment.
Failure to add a Description will show a Value Required message next to the Description field.