I was wondering if there is a certain way in which headcodes (i.e. 1J25) work? For example, looking at http://www.realtimetrains.co.uk/search/advanced/YRK/2015/08/20/0000-2359?stp=WVS&show=all&order=wtt there are various numbers (1, 2, 3, 4 and 5 for example) - 1 and 2 seem to be passenger services, 3, 4 and 5 empty coaching stock - not sure if 1 and 2 are different. I can't work out the letters but the second set of numbers seem to increase per service (so an early service 1E03, a later service 1E23 for example). Purely for my own curiosity!!