Methods and apparatus are disclosed for obtaining and processing information from a predetermined portion of a header of a data item such as an IP packet transmitted via a communication network such as a packet network, the portion carrying a codepoint selected from a first set of codepoints each of which has a pre-defined meaning according to a first pre-defined communication protocol. The method comprises: receiving the data item; inspecting the header whereby to determine the codepoint carried by the predetermined portion thereof; identifying whether the codepoint is a member of a second set of codepoints, the second set comprising fewer possible codepoints than the first set; and in the event that the codepoint is identified as being a member of the second set, and in dependence on such an identification being made, interpreting that codepoint according to a different pre-defined communication protocol as having a different pre-defined meaning and routing the data item via the communication network via the second pre-defined communication protocol.