hi everyone, timberwrestler is right about the O as the waste symbol with the french standard. You can opt to put the depth of the waste in the middle of the "O" is needed or desired.
As far as his source for the markings I would presume you could find that and a wealth of other information in the French encyclopedia of Carpentry. I can find the actual name out it french if anyone would like to know (I did not want to misspell). However it is probably about 10 volumes and is both rare and expensive. I have looked through it with appreciation at the time required for the information (a little befuddled too). It would be worth the purchase if one knew French, eventhough the illustrations are in builders language. I believe that the information for it was most probably compiled starting with the monks of the medieval ages. Passed on, so some standards have been set.
Here are the two most common ones I use when drafting before lay-out.
The gutterline is the level plane at the lowest working point of a rafter. The centerline symbol is frequently used in timber lay-out.
