Pinto bore grading numbers

Just one for curiosity sake.
 
Picked up a 2.0 pinto block during the week. Standard bore, never rebuilt, standard ford pistons and bearings.
 
The bore grading near the distributor were 1112, however next to this was stamped ' 9F19' in the same size digits/numerals.
 
I have never known what the other digits were for or how to decode them.
 
Looking at my other blocks I could see no pattern.
 
What was it for or mean?
 
Thanks, Shaun