esteban,
most likely you have already solved the issue intermediately and surely twice due to the excellent information coming from Milton.
But you know what..?
I have found the symbol you have psoted by having read in an elder (1970's) welding construction textbook today.
The book has dealt with the drawing symbols coming from the "old" German Standard DIN 1912 Part 1 (Fusion Welding).
And voilĂ there it was!
This drawing symbol has defined a "continuously" welded fillet weld. Interesting is, that it was actually unneeded for all cases which define the exact fillet weld details, i.e. making recognizable e.g. its length, etc. So actually it was rather an exception to find it in the drawings.
However, for all cases a fillet joint had to be welded over the whole length the symbol - as posted by you - could have been used for the drawings.
If you would need it, I could scan the original drawings from the textbook and would pass on these information to you.
But as I said. I am certain it will be rather unnecessary.
O.k. that was all and it was just to complete the thread and for your kind information...
Best regards,
Stephan