The OPT pseudo-record provides space for up to 16 flags and it extends the space for the response code. The overall size of the UDP packet and the version number (at present 0) are contained in the OPT record. A variable length data field allows further information to be registered in future versions of the protocol. The original DNS protocol provided two label types, which are defined by the first two bits in DNS packets (RFC 1035): 00 (standard label) and 11 (compressed label). EDNS introduces the label type 01 as "extended label". The lower 6 bits of the first byte may be used to define up to 63 new extended labels.