VERIFIED SOLUTION i

How does MailStream use Label list L602 and L601 and the Mail directional file sortation process

L601and L602 are used to determine eligibility for NDC and ASF discounts, per DMM 246 3.2a. Not the mail direction file.

The mail direction file tells the locale keys for specific USPS entry facilities when you want a discount. The mail direction v3 layout file has this for the first 5 fields.
FIELD RELATIVE
REFERENCE FIELD LOGICAL POSITION
NUMBER DESCRIPTION LENGTH FROM/THRU CONTENT/NOTES
-------- ----------- ------- --------- -------------
1 COPYRIGHT DETAIL CODE 01 001 001 D = DETAIL
2 DROPSHIP ZIP CODE 05 002 006
3 CARRIER ROUTE ID 04 007 010
4 DROPSHIP KEY 09 011 019
5 DISCOUNT TYPE CODE 01 020 020 A = ADC
B = BMC
S = SCF
D = DDU
F = FSS
H = HUB

Field 5 is for a chosen discount. It helps you identify the locale key (and thus the physical facility) that you need to take the mail to for a certain type of discount. It is not at all saying where you *have* to enter the mail.
The mail direction file only lists the ZIP code in question at the ASF because that is the only place it will get the DNDC discount.
UPDATED:  October 2, 2017