4.2. Basic AVP Data Formats
The Data field is zero or more octets and contains information specific to the Attribute. The format and length of the Data field is determined by the AVP Code and AVP Length fields. The format of the Data field MUST be one of the following base data types or a data type derived from the base data types. In the event that a new Basic AVP Data Format is needed, a new version of this RFC MUST be created.
OctetString
The data contains arbitrary data of variable length. Unless otherwise noted, the AVP Length field MUST be set to at least 8 (12 if the 'V' bit is enabled). AVP values of this type that are not a multiple of 4 octets in length are followed by the necessary padding so that the next AVP (if any) will start on a 32-bit boundary.
Integer32
32-bit signed value, in network byte order. The AVP Length field MUST be set to 12 (16 if the 'V' bit is enabled).
Integer64
64-bit signed value, in network byte order. The AVP Length field MUST be set to 16 (20 if the 'V' bit is enabled).
Unsigned32
32-bit unsigned value, in network byte order. The AVP Length field MUST be set to 12 (16 if the 'V' bit is enabled).
Unsigned64
64-bit unsigned value, in network byte order. The AVP Length field MUST be set to 16 (20 if the 'V' bit is enabled).
Float32
This represents floating point values of single precision as described by [FLOATPOINT]. The 32-bit value is transmitted in network byte order. The AVP Length field MUST be set to 12 (16 if the 'V' bit is enabled).
Float64
This represents floating point values of double precision as described by [FLOATPOINT]. The 64-bit value is transmitted in network byte order. The AVP Length field MUST be set to 16 (20 if the 'V' bit is enabled).
Grouped
The Data field is specified as a sequence of AVPs. These AVPs are concatenated -- including their headers and padding -- in the order in which they are specified and the result encapsulated in the Data field. The AVP Length field is set to 8 (12 if the 'V' bit is enabled) plus the total length of all included AVPs, including their headers and padding. Thus, the AVP Length field of an AVP of type Grouped is always a multiple of 4.