Hi Larry,
What I'm betting you are doing is creating a new tag on a file but want to make sure it does not already exist. TAGS are unique to a table so you could not have two with the same name.

To determine if a tag exists use the TAGNO() function. This is poorly documeented but works like this

Select mytable
If Tagno("LASTNAME") = 0
Index on lastname Tag LastName
Endif


Hope that helps.
Rod