When junctioning Mana Eggs, small letters may appear. Some of their meanings are as follows:

R: Adds to range of spells.
MP: The MP cost of the spell decreases.
P: The strength of the spell itself increases.
H: Spells with multiple hits will hit additional times.
W: Spells with an area/fan/around effect will have a wider range.
S: The time it takes to charge the spell will decrease.
IP: The spell will deal more IP damage.