+.DI OCTET
+A single octet, representing a value between 0 and 255.
+
+.DI U16
+A pair of octets, representing a value between 0 and 65535. The more
+significant octet appears first.
+
+.DI U32
+Four octets, representing a value between 0 and 4294967295. More
+significant octets appear first.
+
+.DI "STRING \fIn\fR\fB"
+A string of
+.I n
+octets. A
+.B STRING
+does not have a numeric value.
+
+.DI MP
+A nonnegative multiprecision integer. Let
+.I n
+be the integer to be represented, and let
+.I z
+be the number of octets required to represent
+.I n
+in base-256 format with no leading zeroes; i.e., if
+.I n
+= 0, then
+.I z
+= 0; otherwise
+.I z
+is the unique integer such that
+.ie t 256\*(^(\fIz\fP\-1\*(^) \(<= \fIn\fP < 256\*(^(\fIz\fP\*(^).
+.el 256^{z-1} <= n < 256^z.
+The encoding for
+.I n
+then consists of two octets encoding
+.I z
+as a
+.B U16
+followed by the
+.I z
+octets which are the base-256 digits of
+.I n ,
+most significant first.
+.LE
+
+.T1 "Structured data items"
+
+A
+.I structure
+is a compound object which is simply the concatenation of a number of
+its component objects. Structures are used directly as messages, and
+indirectly as things to be hashed or encrypted.
+
+The notation
+
+.SD
+. ST STRUCT . kx-cookie
+. SR OCTET . 0x11
+. SM MP . c
+. SM STRING 20 hash
+. LE
+.LE
+
+indicates that
+.I msg-cookie
+consists of the two items
+
+
+
+
+.SD
+. ST STRUCT . kx-prechal
+. SR OCTET . 0x10
+. SM MP . c
+. LE
+.LE