oftenintroducingsecurityflawsorinteroperabilityproblemsduetomistakenlyviolatingHTTPsemantics.Forexample,an"interceptionproxy"[[RFC3040](https://tools.ietf.org/html/rfc3040)](alsocommonlyknownasa"transparentproxy
withpossibletranslation,tootherservers.AproxyMUSTimplementboththeclientandserverrequirementsofthisspecification.A"transparentproxy"isaproxythatdoesnotmodifytherequestorresponsebeyondwhatisrequiredforproxyauthenticationandidentification.A"non-transparentproxy"isaproxythatmodifiestherequestorresponseinordertoprovidesomeaddedservicetotheuseragent