G'day Pablo and others,
From another posting, I have encounterd photos of Argentinian lower quadrant semaphores featuring the letter M.
https://www.flickr.com/photos/44833183@ ... otostream/
I am wondering if the M stands for Manoibra (to shunt), and would equate to a Shunt Ahead ?
I have also seen other photos featuring the letter O attached to Argentinian semaphores.
I have also seen this application in Queensland Railway lower quadrant semaphores featuring the O.
The QR meaning being for turnout into sidings.
Steve.