$ cat pm_1077685_A.txt
Line 1: no plate info
Line 2: ... PlateID 123 ...
Line 3: ... PlateID 456 ...
Line 4: no plate info

$ cat pm_1077685_B.txt
Line 1: no plate info
Line 2: ... PlateID 789 ...
Line 3: ... PlateID ...
Line 4: no plate info

$ cat pm_1077685_C.txt
Line 1: no plate info
Line 2: ... PlateID 000 ...
Line 4: no plate info