Odd FROG Desert Marpat Trousers

I got 5 pairs of weird trousers at goodwill today.
They appear to be made with USMC branded flame retardant Desert Marpat cloth. Extra re-enforcement on the knees. Plenty of extra pockets.

Here comes the odd part. They all have no contract labels. Hand written size tags on the back of real size tags (that don't match the size) and some weird code.
Could they be a test run from a manufacturer? A cut sample? Any ideas?

Looks like legit FROG fabric.

Very weird and very interesting..

No clue at all as to what it's purpose might have been, but I like it...

S

Interesting find! Do you see any differences between the lettered types? To me it looks like experimental versions A, B, C, and D with hand written serial numbers.

Steve

Looks like each letter group has the same style writing as the others in it's group. Also each letter group has the same color variance in the fabric. It's slight I don't know if you can see it in the pictures. I'll try and get some that show the difference.
The D group is has distinct olive shades in it rather than brown and tan.
The C group is very similar to regular Marpat with browns and tans.
The B group is much closer to Cadpat AR. More Pink grey/brown and tans.
Past that the cuts are all identical.