Mapping

HI,

I am doing an interface, where files is sender.

but i dont have field seperator like commma or tab. i need to seperate fields by looking at field lengths exampls: field1= first 5 chars

field 2= 6th to 12th char

field 3- 13th to 18th char

how do i manage this in sender communcation channel for file parameters.

Regards,

Jeff