[leovonl]

SOS was meant to be easily recognizable and trivial to generate:

    ... --- ... --- ... --- ... (and so on)

[sverige]

Actually, it is sent sequentially as a single nine-digit signal, then repeated. Graphically this looks like ...---... ...---... ...---... and so on.

Incidentally, graphical representations of Morse code are weak tea. It has to be heard to be understood.