Recast is used when you add or remove parameters to a preset.
For example let's say you save an all preset with only Pan and Tilt information and store that into a cue. Now you edit that same All Preset updating the position and adding Color Data, when you look at the cue where the preset is used it only contains the updated position data and not the color Data. In order to include this new data in the cue you would recast the preset thus adding the new values to the cues holding the preset.
If MA2 you have to selectively update the cues with an IF statement to call the updated preset into each cue.
Thanks~ 
