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Signalling Instructions · 1935
S.P. 02201 is the reference number of a set of Signalling Instructions
for encoding and decoding messages, issued by the Admiralty of the British
Navy on 1 October 1935. The instructions are divided in four parts, of which
Part I and IV are bundled in the book featured here.
In the context of this section of the website, the S.P. 02201
is considered to be a procedural codebook.
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The book is marked CONFIDENTIAL and contains references to penalties
under the Official Secrets Acts, if confidentiality is not respected.
For this reason, each copy is numbered individually. The copy shown
here has serial number 6158
[1].
According to a note on the first page,
the cover is weighted with lead, to ensure that it sinks
when thrown overboard. The book is
signed by Sir Oswyn Murray 1 of the Admiralty,
with strict instructions that every precaution had to be taken to ensure
that the book - and any other signal book – would not fall into enemy hands.
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It contains detailed instruction on how to create a message, with the
appropriate fields in its preamble, such as the time of origin (TOO), the
addressee and the recipient. It provides instructions for coding and
decoding, sending status and weather reports, and for giving each message the
desired priority. As with all Naval instructions, the procedures are
worked out to the finest detail.
When security was compromised, the codebook had to be destroyed immediately,
so that it could not fall into enemy hands. The preferred method for this
was to destroy it by means of fire. The second best method, if no fire was
available, was to throw it overboard. As the covers of the book are filled
with thick lead panels, the added weight will cause it to sink immediately.
The book was introduced at the British Navy in 1935, and was used
throughout WWII, as indicated by the
many corrections and inlays that were
added in 1943 and particularly in 1944. It was also used by the Dutch Navy
(Koninklijke Marine), which was the only part of the Dutch Armed Forces
that was still operational during WWII,
when the country was under German occupation.
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Sir Oswyn Alexander Ruthven Murray GCB (17 August 1873 - 10 July 1936)
was a British civil servant who spent most of his career at the Admiralty,
serving as Permanent Secretary from 1917 to 1936.
➤ Wikipedia
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- General Signalling Instructions
- Visual Signalling Instructions (O.U. 5366) 1
- Wireless Signalling Instructions (S.P. 2203) 1
- Coding and L/T Instructions
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The following expressions and abbreviations are used in the book. They
are listed in Chapter I — Technical Definitions, and the user is assumed
to be familiar with them when using the book.
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L/T
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Line Telecommunications
All methods if communication by land line or submarine cable, including
telephone, teleprinter and Morse telegraphy.
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P/L
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Plain Language
Any recognised language used for a message, whereby the meaning is
intelligible without the assistance of a decode (or decypher).
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R/T
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Radio Telephony
Method of passing speech by means of electro-magnetic waves which can
only be rendered perceptible by electrical devices.
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S/S
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Sound Signalling
Method of passing message in morse code
by means of a siren, fighorn or whistle.
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S/T
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Sonic Telegraphy
Method of passing morse signals
through the water by means of sonic waves.
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V/S
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Visual Signalling
Communication of message by sight. This includes gestures, flag signals
and sometimes also Sound Signalling (S/S).
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W/T
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Wireless Telegraphy
Communication of the message by electro-magnetic waves, or by
sonic waves through the water (S/T). Messages sent by W/T, R/T or S/T
are therefore all regarded as W/T messages.
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THI
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Time of Handling In
The time at which a message is handed over to a Cable or Telegraph office
for transmission by L/T or Commercial W/T. It appears on the delivery copies
of these messages.
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TOD
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Time of Despatch
The time at which the transmitting ship clear a message. In messages to more
than one receiving ship there may be more than one TOD.
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TOO
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Time of Origin
The time at which a message is authorised, except in F/F and Enemy reports,
whe, in the absence of a definite statement to the contrary, it is the time
at which the occurence forming the subject of the report was actually observed.
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TOR
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Time of Receipt
The time at which the receiving ship completes the receptionof the message.
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- Anonymous, S.P. 02201 Signalling Instructions Part I and IV
Retrieved October 2010.
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© Crypto Museum. Created: Saturday 08 July 2017. Last changed: Wednesday, 17 November 2021 - 07:41 CET.
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