Messages
The vectors point to the first word of the message, occupied by a message header. This header contains more information about the message (or message fragment). For Alphanumeric messages, the header looks like this
+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+------------+--------+ | k0 | k1 | k2 | k3 | k4 | k5 | k6 | k7 | k8 | k9 | c0 | f0 | f1 | n0 | n1 | n2 | n3 | n4 | n5 | r0 | m0 | 10 bit CRC | parity | +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+------------+--------+
- k 10-bit fragment check word
- c 'message continued'-flag. If this flag is set, fragments of this message will follow in the next frames
- f 2 bit fragment indicator, starts with 3 for the first message. This value is skipped when counting the next fragments
- n 6-bit message number. I've really only seen the number 0, but maybe that's just me
- r retrieval flag; this flag is set if the pager should keep track of message numbers, in order to detect missing messages
- m mail drop flag, not entirely sure what it's supposed to do
Additionally, for the first fragment, a 7-bit signature is included as part of the second word in the message.
+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+------------+--------+ | s0 | s1 | s2 | s3 | s4 | s5 | s6 | a0 | a1 | a2 | a3 | a4 | a5 | a6 | b0 | b1 | b2 | b3 | b4 | b5 | b6 | 10 bit CRC | parity | +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+------------+--------+
- s 7-bit signature, containing the sum of all subsequent 7-bit characters
- a 7 bits of data, first character of the message
- b second character
All other following 32 bits words contain 3 7-bit characters