Unusual markings on '71 383 block

In cleaning up what I believe to be a '71 383 warranty block (blank VIN pad, never stamped), I found some interesting markings on the data pad by the distributor

The G383 is straightforward, as is the 12 14 date (10/70 casting), but what are the punch marks below that?

It appears to be 'F' 'R' (factory replacement?), but it's sloppy enough that it could be anything.

Insights would be appreciated.

Thanks in advance

I think somebody just punched their own initials into the ID pad, to make sure they got their own engine back, if was sent out for work anywhere.
Or punch mark initials, of someone that did work on it.
I used to do stuff similar to that, when i sent out parts for other shops to work on stuff.

Vlad I haven't seen every nor followed every thing on a what constitutes a warranty/service replacement/over the counter block or short engine BUt that engine being stamped G383 and the assembly date makes it , to me , a production line 2bbl block that for whatever reason didn't get a VIN put on it.

A warranty/service replacement/over the counter shouldn't/wouldn't have a model year stamped on it unless one was pulled from the production line to fill a warranty request ???