Use 'bw' and prepend '==' to finding value.
jhunter does not specify if this is URL or FORM request, so I'll expound on user19752's reply:
the nature of requests is that if you use the SAME field more than once the request is concatenated:
FORM: input type=hidden name=abc value="=="
input type=hidden name=abc value="String"
both of these actually SEND the request so that "abc" is really:
u. said to use the 'bw' operator and prepend the "==". since by default all requests in FileMaker are 'bw' (begins with), this is an unnecessary step. just prepend the "==". NOTE the URL encoding of the character "=" as "%3D" in the URL format of the request.