It is but it will require you to do some programming.
The xml being processed by the xslt will contain a /b:Citation/b:PagePrefix element if you specify a \f. But without testing I would expect that element to be empty if you didn't provide an actual prefix. You would be better of using one of the suppression flags (/b:Citation/b:NoAuthor, /b:Citation/b:NoTitle, or /b:Citation/b:NoYear).
In BibWord, the format-citation is responsible for all formatting of in-text citations. You will find the different flags being used in there if you want some examples.
The xml being processed by the xslt will contain a /b:Citation/b:PagePrefix element if you specify a \f. But without testing I would expect that element to be empty if you didn't provide an actual prefix. You would be better of using one of the suppression flags (/b:Citation/b:NoAuthor, /b:Citation/b:NoTitle, or /b:Citation/b:NoYear).
In BibWord, the format-citation is responsible for all formatting of in-text citations. You will find the different flags being used in there if you want some examples.