Flat File definition question

I have a flat file that needs to be mapped, and it has a format similar to

F1 - “XX” char(2)
f2 - some_value char(6)
f3 - some_value char(8)
rp1 - some_value char(2)
rp2 - some_value char(2)
f4 - some value char(2)

where each line will start with an “XX”, the first three fields are fixed length, then I can have any number of rp1 and rp2 repeating with no tag to indicate that it is the sequence, followed by another field after the repeatable sequence.

I hope this isn’t too confusing, and if anyone has any ideas, I would greatly appreciate the help.