I would be inclined to disagree, actually, for the simple reason that DL's routing rules for international travel are almost exclusively based on MPM. Find me a DL fare (not a KL fare) for US-EU that lists the routing other than MPM and ticketed point deductions. That makes it impossible to determine what falls within a published fare. If DL.dumb supported more partners, it might be possible to test this theory out, but with just DL, AF, KL, AS, and HA, I'm not sure I can come up with a good example. The one I'd like to try is
BOS-DL/AF-CDG-AF/KL-AMS-KL-OSL-OK-PRG-OK-ZAG
to address yesterday's example. EF reports:
Results from ExpertFlyer.com
Code:
Maximum Permitted Mileage:
Airports: BOS-CDG-AMS-OSL-PRG-ZAG
Flying DL on 09/01/11
Maximum Permitted Mileage
BOSZAG-DL 01SEP11
TICKETED POINT SURCHARGES APPLY.
GI M 5M 10M 15M 20M 25M
MPM AT 4929 5175 5421 5668 5914 6161
Calculated Sector Mileage
BOS DL PAR DL AMS DL OSL DL PRG DL ZAG /01SEP11
*************************************************************
CTY GI TPM CUM MPM EMS DED LAST NEXT 25M
BOS 1
1. PAR 2 AT 3444 3444 4132 0M 0 0 688 5165
2. AMS 2 AT 247 3691 4138 0M 0 0 447 5172
3. OSL 2 AT 597 3688* 4219 0M 600 0 531 5273
4. PRG 2 AT 710 4398* 4664 0M 600 0 266 5830
5. ZAG 2 AT 313 4711* 4929 0M 600 0 218 6161
* TICKETED POINT DEDUCTION APPLIED
Note that this cuts out your proposed backtracking through AMS, which I think was what was causing the system to have fits. Using the TPDs, that should be a valid routing, allowing a stopover in OSL.