I am still figuring out how the mileage accrual works on United.

Please correct me if I am wrong, but the impression I am getting is that the following rules are in effect:

a) purchase an international ticket on UA flights on UA ticket stock and UA coded flights.
-> mileage earned is calculated on the sum of the fare and the YQ amount.
b) purchase an international ticket on Ua flights which are coded as UA flights, but on non-UA ticket stock.
-> mileage earned is calculated on the base fare, and the YQ amount is not factored in.

If the observed rules are true, it could be very advisable to not book UA flights on non-UA ticket stock.

Could someone confirm or disprove my observations?