[AccessD] A2000: Import Needs

Hi all
 
I have been given large (very large) text files to manipulate
 
I can Import them using the fixed width method and I can even attach them using
the get External data wizard - It all works OK
 
But the issue with these files is that one file may contain different data types
- all determined by a 3 character code in the first 3 positions in the left most
position of each line
 
EG we may have 3000 lines of data that start with "ABC" - Cool - I can create an
import spec - Call it the ABC import spec and break up each line into the
relevant fields in a table using fixed width - Easy
 
But after the 3000 "ABC" data type lines in my text file - there may be 1200
lines that start with "DEF" as the left most 3 characters and the data in each
of the "EFG" type lines need to be 'mapped' at different fixed lengths into
different fields
 
So the issue is - has anybody had experience kind of 'merging' several Import
Specs but only across 1 file?
 
Or does anyone have any suggestions on handling this?
 
Many thanks in advance
 
Darren