Again...A few years ago when Block-II had shown up, we learned that Block-I will be upgraded to Block-II standard and the Block-II will be PAF's baseline model of JF-17.
If this is true, then:
Block II = JF-17A
Block-II twin-seat = JF-17B
Block-III = JF-17C
Block-III twin-seat = JF-17D
F-16s too uses A/B/C/D/E nomenclature.
You made this up.
What is block 1 jf17?? You forgot? Or it didn't fit your rationale