Back on 27 March 2015 the following was written in Alpha Strike Rules questions:
The spotter (and attacker) movement modifers do apply to IF.
Posting errata.
In this thread,
http://bg.battletech.com/forums/index.php?topic=45559.0I don't see that this made it into the errata, and the Alpha Strike rulebook (2nd ed) p 35 states, "Indirect fire attacks use the range modifier of the attacking
unit, the movement modifiers of the target, and terrain modifiers based on the spotter’s LOS."
Question - Is applying the spotter's movement modifier to IF correct, or was it later decided this was not the case (and therefore not entered into errata)?
(I was involved in a discussion about this recently. It was also discussed that if the spotter's movement modifier does apply to an IF attack, should not the spotter's skill affect IF also?)