When coding some complicated extracts, or adding numerical filters it would be nice to add a comment to the line to remind you 'why' you are extracting that field, or how a compound (group) field is being extracted that way.

IE - 'Building Student Login ID from 1 char of FN, then Student ID for a A01234567890 formatting login. OR 'Default student password is MI or 'N' if no MI plus DOB in MM-DD-YYY format for a A01-02-2003 formatted password.

OR - Add a large open textbox, optional of course, at the top where you can add things like, Who asked for the extract, what program it is for (The 'Interface Description' is too short), what needs to be changed every year, who the vendor contact may be etc...
This will assist when you have to come back later and work on an extract.