Technical References

AT_STIME (stime)
A signed version of the AT_TIME type that allows negative time spans. The main use of this
type is for time-zone offsets that may be positive or negative.
AT_STRING (string)
A null-terminated sequence of ASCII bytes.
AT_STRUCT (struct)
Deprecated.
AT_SUBNET (subnet)
An IPv4 address and a count of the bits that comprise the network number. The address
component will have its host bits set to 0. A similar type,
AT_IPNET does not assume or require the
host bits to be 0.
AT_TEXPR (texpr)
A typed expression; its structure and representation is the same as an
AT_EXPR but the extra
value of the attribute contains the expected type of the value produced by evaluating this expression.
AT_TIME (time)
An unsigned integer number of seconds. It differs from the
AT_DATE type in that it encodes a
span or duration of time rather than an exact point in time. Format is 'HH:MM:SS'.
AT_TLV (tlv)
A generic type-length-value tuple, in which the 'type' and 'length' are each one octet long.
AT_TLV2 (tlv2)
A generic type-length-value tuple, in which the 'type' and 'length' are each two octets long.
AT_TLV4 (tlv4)
A generic type-length-value tuple, in which the 'type' and 'length' are each four octets long.
AT_TYPECNT (type-cnt)
This is a special-purpose type used in configuring DHCP options used by PXE clients. It holds a
repeating pattern of tuples, each consisting of a two-octet type, a length byte, and 'length' bytes of data.
AT_VENDOR_CLASS (vendor-class)
An
AT_BLOB representing a DHCP vendor-class option. An enterprise ID is followed by
opaque data. (If DHCPv4, the enterprise ID is followed by an EID length.)
AT_VENDOR_NOLEN (vendor-nolen)
An
AT_BLOB representing a DHCP vendor-class option. An enterprise ID is followed by tuples
of vendor-specific data. The enterprise ID is never followed by an ID-length.
AT_VENDOR_OPTS (vendor-opts)
An
AT_BLOB representing DHCP vendor-specific options data. An enterprise-id that is followed
by TLVs of vendor-specific data. If DHCPv4, the enterprise ID is followed by an EID length.
AT_VERSION (version)
A two-component 32 bit number, with 16 bits of major version and 16 bits of minor version.
AT_VPNID (vpnid)
A 7-byte standard VPN ID, as defined in RFC 2685.
AT_ZEROSIZE (zero-size)
A sequence of bytes representing certain DHCP options that have an option code and a length,
where the length is always zero.