Bit Message Bit Message
Elementary
English

The Bit Message is a message that is hidden within the lines of an octet stream and it is represented as a hexadecimal string which has maximum length of 149 octets. The first 9 octets of the message contain the header for the message and the rest comprise the content. The header contains 1 type octet, 7 timestamp octets, and 1 message length octet. The content contains a maximum of 140 octets and could be packed with either 7 bit, 8 bit or 16 bit. 7 bit packed messages have a length of 160 characters, 8 bit packed messages have a length of 140 characters, and 16 bit packed messages will only have a length of 70 characters.

Here are some details on the structure of a bit message:


BIT MESSAGE FORMAT












Bit 7 6 5 4 3 2 1 0

Octet-nth









HEADER







TYPE









YEAR









MONTH









DAY









HOUR









MINUTE









SECOND









TIMEZONE









LENGTH

CONTENT







Octet-1

...







...









Octet-140























7-BIT PACKED MESSAGE












Bit 7 6 5 4 3 2 1 0

Octet-nth









1 0 b6 b5 b4 b3 b2 b1 b0


































8-BIT PACKED MESSAGE












Bit 7 6 5 4 3 2 1 0

Octet-nth









1 b7 b6 b5 b4 b3 b2 b1 b0


































16-BIT PACKED MESSAGE












Bit 7 6 5 4 3 2 1 0

Octet-nth









1 b7 b6 b5 b4 b3 b2 b1 b0

2 b15 b14 b13 b12 b11 b10 b9 b8

































HEADER # OCTET DESCRIPTION







TYPE 1 contains specific flag for specific format identifier








DETAIL





Bit 0-1 : reserved message class meaning

Bit 2-3 : message encoding


Bit 3 Bit 2 Pack



0 0 7 bit



0 1 8 bit



1 0 16 bit



1 1 reserved








Bit 4 : reserved flag message class meaning

Bit 5 : reserved message is compressed or uncompressed

Bit 6-7 : reserved general data coding














TIMESTAMP 7 contains specific swapped nibbles for specific format identifier







DETAIL





Octet 1 YEARe.g. 10 for 2001

Octet 2 MONTHe.g. 10 for Jan

Octet 3 DAYe.g. 10 for 01








Octet 4 HOURe.g. 10 for 01

Octet 5 MINUTEe.g. 10 for 01

Octet 6 SECONDe.g. 10 for 01








Octet 7 TIMEZONEe.g. 80 for 08 x 15 / 60 = +2


The Time Zone is GMT format, expressed in quarters of an hour. In the first of the two semi-octets, the first bit represents the algebraic sign of this...















LENGTH 1 maximum characters allowed is 160, 140 or 70 characters depends on message packed format






































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