APL mangled the 2nd Ed rules pretty well. However, they did not change the fire types.
The big thing that got left out for artillery is Open Sights missions. That is how on-board artillery and mortars worked, or they could get a bombardment mission, like the off-board artillery. You can still download a copy of the
1st Edition rules here.
One of the rules left out of the 2nd Edition is:
10.3 Open Sights Missions.
Artillery units with Open Sights missions (9.12) may fire at enemy units and/or leaders they can spot using the same procedure as for units with direct fire values (10.2), but they roll on the
Bombardment Fire table and use the column modifiers from that table.