Typically, such markings are used for equipment and/or part identification within the foundry and that's all. The employees may not know a head from a water pump but they easily understand a designation like b-1 (which would be a unique designation for that particular part within the foundry).
On the other hand, the B-F on the Brumfield Heads serves a dual purpose but this is not the norm for most castings.
I also notice a small raised square with some markings embossed on the head over near the side and it looks like a couple of small knob embossments as well, one each on either side of the dist. hole.