What is this about?
Sprite alignment can become a real pain, especially if it comes to train sets where the sprites all have to find a common alignment while they all may be of different sizes.
Using templates for pcx and offsets
One solution in order to simplify coding and reduce the time spent on fixing different offsets is actually to use a standard layout in which sprites are arranged in the image (pcx) file and then use always the same offsets, using 'templates'. OpenGFX uses for all trains a common layout which works like this: The graphics of a single engine go into a separate graphics file with a common layout:
and the filled-out versions with the sprites put in look like
or 
Pay attention that the vehicles are arranged such that the upward travelling view is aligned to the bottom and the downward travelling one to the top of the sprite, generally the back of the vehicle touches the blue box' border while in the front we can allow to leave some space for slightly shorter vehicles. Adjustments for really shorter vehicles are described further down.
Then we can write the offsets for these sprites as
-1 TRAIN_88.pcx 0 0 01 24 8 -3 -13 -1 TRAIN_88.pcx 9 0 09 20 22 -13 -11 -1 TRAIN_88.pcx 32 0 01 17 32 -16 -12 -1 TRAIN_88.pcx 65 0 09 20 22 -5 -11 -1 TRAIN_88.pcx 88 0 01 24 8 -3 -11 -1 TRAIN_88.pcx 97 0 09 20 22 -13 -11 -1 TRAIN_88.pcx 120 0 01 17 32 -16 -12 -1 TRAIN_88.pcx 153 0 09 20 22 -5 -11
or - for symetric sprites we only need four views when we arrange them in the centre of the blue boxes:
-1 TRAIN_88_SYMETRIC.pcx 0 0 01 24 8 -3 -13 -1 TRAIN_88_SYMETRIC.pcx 9 0 09 20 22 -13 -11 -1 TRAIN_88_SYMETRIC.pcx 32 0 01 17 32 -16 -12 -1 TRAIN_88_SYMETRIC.pcx 65 0 09 20 22 -5 -11