My pleasure.
The Chinese have a system, as far as I can ascertain, using prefix for the type followed by a batch and sequence number.
Prototypes do not have a batch number, so after the prefix usually have some zeros and then a sequence number.
The prototypes and preproduction single seaters are FC10001 to FC10010 and the dual seaters are BC0001 to BC0003. The production aircraft are FC10101 and BC010001 and so on.
During production in China, CAC applies these on the primer airframes.
Also, PAC uses these during assembly, on paper stuck to the plane. See:
)
During test flights in China, sometimes just the batch and sequence number is painted on in big red numerals (like with JF17 213 and 229, I think photos exist of those.) The prototypes only use the last two (there is no production batch number, so that part is omitted from protypes), so 01, 02, 03. And yes, 3000 is bit a-typical, that is why I think it may be a 'hybrid' aircraft used as pattern aircraft for avionics, so not 001 but 000...
During production in Pakistan the P-xx (for Block I), 2P-xx (for Block II) and 2P-xxB (for Block II B) are used while the aircraft are entering flight test in primer.
After painting in grey, they receive the FC1 numbers, painted in small numbers on various places.
FC10101 and so on for Block I, FC10201 and so on for Block II.
I have not seen a BC01 number on a grey production aircraft yet.
Only BC0003 on pre-production 19-602 (so: ex '03').
Export aircraft may be in this FC01/BC01 sequence too, but when the configuration is different, that will be reflected in the production number. So, the Myanmar single seat aircraft are FC15201. The 5 has something to do with the Ruby subtype, the 2 is for Block II and 01 is the first in that batch. Or the 5 can be the 5th configuration (block 1 to 3 for PAF, 4 for Nigeria, 5 for Myanmar who can tell??)
So some clarification and some more puzzles, sorry about my lack in understanding Chinese logic for those