Dances with Squirrels spiked it!
"Set - The result, mostly due to belly compression/compaction, of a bow’s inability to return to its original shape after use. For instance, if a bow was constructed from a bow stave with 3” of reflex and after tillering, shooting in, and unstringing, the bow then shows 1” of reflex, the bow is said to have taken 2” of set."
String follow is how much the bow looks like it's strung when it isn't as caused by tillering.
Deflex (bend towards the string" is heated in or natural.
All I can say is "Set happens!"
Jawge