Graphic symbols on early movements

Some thought it referred to the ligne o(size) of the movement, but as can be seen, the ligne is otherwise marked in some.

Lost in the mists of time, as is true of so much Bulova information.

Great pictures....and a great mystery.  I've seen various markings on these older movements.

I asked if anyone knew what the marks could be on WUS, where there are many experts posting regularly including Roland Ranfft, and none seem to know. At least, none have answered as yet.

http://forums.watchuseek.com/f11/bulova-movement-marks-1059292.html

I suspect this was an in house marking by Bulova, to either identify the ebauches and/or indicate what would be done to it by way of modifications. Bulova invariably always modded the movts, and finally took this all the way, finally to the US built ones. 

We're only guessing here, but my bet is on a factory series or code that was used to ID either the mods, or perhaps even to what lines of watches they were destined for. Another possibility is that the ebauches were themselves specially marked upon shipment to Bulova, and may be factory codes that ID'd the customer and what the customer had specified, the customer being Bulova. So FHF might make an ebauche which already was specially set up for balance mods or a top plate mod, and this was their way of keeping track in the factory. 

All speculation, of course.