TLV

Type(Tag), Length and Value

Within data communication protocols, TLV (type-length-value or tag-length-value) is an encoding scheme used for optional information element in a certain protocol.

The type and length are fixed in size (typically 1-4 bytes), and the value field is of variable size. These fields are used as follows:

Type\ A binary code, often simply alphanumeric, which indicates the kind of field that this part of the message represents;\ Length\ The size of the value field (typically in bytes);\ Value\ Variable-sized series of bytes which contains data for this part of the message.