I have been sent a clip of a drawing with the following annotations on it, but I've never seen them before and can't figure out what they mean. Is there a standard interpretation of these callouts?
Initially I thought that they might be some metric notation for I beams with the height shown in mm, but weld callouts on the drawing use fractional inches and american electrode designations. Furthermore the members they refer to are rectangular and square tubes, not I shapes.
There is some ambiguity if the material in question is steel or aluminum (an email said aluminum but the electrodes for welding are steel.)
I will obviously also contact the person who provided the drawing, but they got it third hand so it may take a long time to get to the source.