As long as the document contains data in the form of a table with the first
row of the table being the names of the mergefields, it can be used as a
datasource.
You cannot specifically save any file, other than a main doc, as a main doc.
So, I am not really sure what you think that you did.
If what you have is a document full of labels that you would like to convert
to a data source, then:
See "Convert Labels into Mail Merge Data File" on fellow MVP Graham Mayor's
website at:
http://www.gmayor.com/convert_labels_into_mail_merge.htm
--
Hope this helps.
Please reply to the newsgroup unless you wish to avail yourself of my
services on a paid consulting basis.
Doug Robbins - Word MVP