M10 was run by the Czech Military Intelligence (Czech: Vojenské zpravodajství). Morse code counterpart to S10d. Active since mid 1970s (multiple formats) until 20 June 2007.
|555||630||26||630||88||26||= =||22681 22681 01927 01927 ...||= =||88||26||0 0 0|
|3-figure arbitrary ID||3-figure recipient ID||Amount of 5-figure groups in the message||3-figure recipient ID||2-figure number, purpose unknown||Amount of 5-figure groups in the message||5-figure paired groups||2-figure number, purpose unknown||Amount of 5-figure groups in the message|
|Repeated thrice||Repeated thrice||Repeated thrice||Repeated twice||Repeated twice||Repeated twice||Repeated twice|
|Repeated for 5 minutes|
M10's intro, preamble and outro were sent at 15 WPM, while the message groups were at 20 WPM. Zero was sent as T - a single dash. M10 often sent more than one message in one transmission to more than one recipient. In that case, in the intro, the ID's and the group counts were included for all the messages, in the same way as the first one. Then the preamble, the message and the outro except "0 0 0" followed for each message. The last message ended the transmission with "0 0 0".
From 1990 to 2006, the arbitrary ID was only 555. Then from 2006 until the station's demise random triplets were used, but never 555.
M10 had a large amount of schedules at all times of day, which outnumbered those of S10d. On many schedules, the messages were usually first sent in the morning, and repeated later in the evening. M10 could have started at any 5-minute interval within an hour, and was usually, but not always, transmitted on two frequencies in parallel.