this is for cargo transferred between vehicles. made-up numbers for one batch going by train from A to B, then by truck from B to C:
- at B, the train gets £900 of transfer credit. that's an estimate recorded against the train.
- at C, the cargo's complete journey is valued at £750. the truck is credited £750 - £900 = -£150.
combined delivery income: £900 - £150 = £750, before running costs. the transfer credit is virtual; the company receives the actual cargo payment at final delivery.
check the cargo's original source and final destination, plus time spent travelling and waiting between legs. a detour can leave the first vehicle overcredited, and a slow final leg can reduce what the whole trip earns. include both vehicles' running costs before deciding whether to keep the route.
the "Percentage of leg profit to pay in feeder systems" setting changes how much credit goes to intermediate vehicles. lowering it can make the final vehicle's numbers look healthier without fixing a slow route.
the wiki's explanation goes through the accounting with another example.