ENVIRONMENT:
OS Name        Microsoft Windows XP Professional
Version        5.1.2600 Service Pack 1 Build 2600
MS Word                 Microsoft Word 2002 (10.2627.2625) or
                             Microsoft Word 2000 (9.0.4402 SR1)

A primary mail-merge document includes text from another MS Word document;
that is, the primary/main document contains the includetext - something like
this.
    {INCLUDEXT ANOTHER.DOC}.
ANOTHER.DOC contains a number of ASK and FILLIN fields.  For example {ASK
MYCODE “Enter a code” \o}  Or {FILLIN “Enter value” \o}.
The ASK and FILLIN fields are coded inside the ANOTHER.DOC with ask once
code (\o).   When mail merge is executed the user is correctly prompted once
for
the ASK and FILLIN fields, but the result is incorrect because only the
first copy of the merged letter, the copy for datasource record 1 contains
the populated data from the ASK and FILLIN fields, and the subsequent copies
of the letter (for datasource records 2 to n) contain blanks in place of the
ASK and FILLIN field values. That is, the mail merge populates the ASK and
FILLIN fields with ask once switch for the first datasource record and fails
to populate the values in the subsequent records.
I am not sure if I am doing something incorrectly or discovered a limitation
(bug)?  
Any help would be greatly appreciated.