A Rawlings date code question

I still can't figure out these Rawlings date codes. I apologize for this.
I have a black made-in-USA HOH Rawlings PRO-TF B with a Trap-EZE web purchased in 1987 in Reading, PA.
The code on the thumb is "HBB01".
What does this signify?
Also, I believe this to be Horween leather. Is it? It felt like iron plate when I bought it, and to this day, this is my all-time favorite leather.
Thank you,
John
I have a black made-in-USA HOH Rawlings PRO-TF B with a Trap-EZE web purchased in 1987 in Reading, PA.
The code on the thumb is "HBB01".
What does this signify?
Also, I believe this to be Horween leather. Is it? It felt like iron plate when I bought it, and to this day, this is my all-time favorite leather.
Thank you,
John