Imagine we can define some troops classes (categories),
like Levy Infantry, Infantry, Levy Missile, Missile & Heavy Infantry .
Each settlement size 'raises' different number & above categories of troops.
It's shown on below table :
.
So in particular scenario (AI vs Player, ... ) in particular settlement size, script will create given number of units.
Units will be created in order specified in the last column.
So Heavy Infantry unit will be added ONLY when Player is besieging AI.
+Plus means that unit will be given experience bonus.
Each Faction 'implements' those troops classes in a different way.
It's shown on table in
pdf or
excel (second tab) .
Unit names are from export_descr_unit.txt (EDU) so they're 'technical names'.
Some names are explained in mini-tablein pdf (below main table).
+1 / +2 means that unit will be given +1 / +2 experience bonus. (cumulative with settlement sizes table).
Slav Levies (serbia) - means that Slav Levies unit would be raise only in regions with "serbia" hidden resource present.
So local or AOR like garrisons are possible & already many such troops are in above table.
As you see - these are mostly light weight Levy / Militia / Urban Militia troops.
See discusion in this thread for reference.
Only few factions has access to Levy Missile in every settlement.
But Berber Archers is AOR style 'Levy Missile'. Each settlement with 'berber' hidden resource will be able to raise it as garrison troop.