The Method token indicates the method to be performed on the resource identified by the Request-URI. The method is case-sensitive.
Method = "OPTIONS" ; Section 9.2
| "GET" ; Section 9.3
| "HEAD" ; Section 9.4
| "POST" ; Section 9.5
| "PUT" ; Section 9.6
| "DELETE" ; Section 9.7
| "TRACE" ; Section 9.8
| extension-method
extension-method = token
The list of methods allowed by a resource can be specified in an Allow header field (section 14.7). The return code of the response always notifies the client whether a method is currently allowed on a resource, since the set of allowed methods can change dynamically. Servers SHOULD return the status code 405 (Method Not Allowed) if the method is known by the server but not allowed for the requested resource, and 501 (Not Implemented) if the method is unrecognized or not implemented by the server. The list of methods known by a server can be listed in a Public response-header field (section 14.35).
The methods GET and HEAD MUST be supported by all general-purpose servers. All other methods are optional; however, if the above methods are implemented, they MUST be implemented with the same semantics as those specified in section 9.