Instructions / contact
The exact semaphore protocol seems to vary with each institution that uses/used it (navies, armies, Boy Scouts etc.), particularly in the details regarding setting up the message and acknowledging it after sending. This software simply does an "attention" signal (also sometimes used mid-message as an error signal) at the start and end of the message. Some protocols acknowledge this attention signal with a dropping of the flags (which can be input here with a + (plus) sign).
Another form used for error (8 or more E signals) can be sent by using ~ (tilde) as an input letter. Yet another is "annul", which can be input with ? (question mark).
There is no such thing as case in flag semaphore: like Morse code, both upper case and lower case are the same. Also note that semaphore is not "handed" (i.e. it is the positions the two flags occupy which matters, not which hand holds which flag ); skilled operators (and this software) take the shortest combined path to flags' new positions even if this means the arms cross the body.
Semaphore has some signals doing double duty as both letters and numerals. As stated above, this software does not need explicit use of the "letters" and "numerals" precursor signals (it will put them in automatically), but these flag positions can be input explicitly if needed with J and # (hash), respectively. A space/rest is sometimes considered an implicit return to letters in semaphore protocols, so, for the sake of unambiguity, this software sends a # signal before each contiguous run of numerals.
To summarise, special characters used in this software [signs/signals in square brackets are not used in this software]. Descriptions are from the observer's point of view:space – end of word/sentence; rest. Both flags down. J – letters to follow (put in automatically by this software).# – numerals to follow (put in automatically by this software). Unlike its partner, J, this is a unique position with one flag straight up and the other at 45° to the right of it. [Some protocols use crossed flags above the head for this purpose.]! – attention; start message; end message; error. Flags waved up and down several times. [Some protocols signal end of message with "short vertical opposite-direction arcs on left-hand side of body".]+ – acknowledge attention and go ahead (if at start. Some protocols signal an R instead); acknowledge end (if at end. Some protocols signal an R or C instead). Flags straight up and then dropped. ~ – error. Eight or more E letters. [Some protocols use a single E with circulating motion on the raised flag.]? – annul/cancel. One flag 45° to the left of upright, the other flag diagonally opposite.
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