Leaders and OP fire.

[Big Ivan]

Yes, in John Tiller's Campaign Series you cannot target leaders with direct fire by themselves unless they are alone in a hex. If they are with another unit, incoming fire will hit that unit if it is known and the leader may share the fate of the unit being attacked. Otherwise there won't be an attack. See section 6.0 page 69 of the manual.

In Campaign Series Middle East however you can target leaders by themselves exclusive of other units in a hex.

Hope this helps!