Keeping content in a file from being searchable by search engines

We have a help project that we don't necessarily want the contents of to be discoverable by search engines. Is there some code that can help us accomplish this? I know that keywords and indexterms help improve visibility, but we want the opposite. Any suggestions? Focus Areas: BPEL | DITA | ebXML | IDtrust | OpenDocument | SAML | UBL | UDDI
OASIS sites: OASIS | Cover Pages | | AMQP | CGM Open | eGov | Emergency | IDtrust | LegalXML | Open CSA | OSLC | WS-I