This file defines how many proficiency points a character can be assigned at his/her creation and later levels.
First column is the list of classes identifiers
2nd column is the maximum number of proficiency points given at the PC creation from the class defined in column 1st.
In IWD2 we have:

2DA V1.0
0
           FIRST_LEVEL 
MAGE       1           
FIGHTER    2           
CLERIC     1           
THIEF      1           
BARD       1           
PALADIN    1           
FIGHTER_MAGE 2           
FIGHTER_CLERIC 2           
FIGHTER_THIEF 2           
FIGHTER_MAGE_THIEF 2           
DRUID      1           
RANGER     1           
MAGE_THIEF 1           
CLERIC_MAGE 1           
CLERIC_THIEF 1           
FIGHTER_DRUID 2           
FIGHTER_MAGE_CLERIC 2           
CLERIC_RANGER 1           
SORCERER   1           
MONK       1           
FIGHTER_MERCENARY 1           
FIGHTER_WIZARD_SLAYER 2           
FIGHTER_KENSAI 2           
PALADIN_CAVALIER 1           
PALADIN_INQUISITOR 1           
PALADIN_VOTARY 1           
RANGER_ARCHER 1           
RANGER_STALKER 1           
RANGER_GIANT_KILLER 1           
THIEF_ASSASIN 1           
THIEF_ARCANE_ROGUE 1           
THIEF_SWASHBUCKLER 1           
BARD_BLADE 1           
BARD_RIDDLEMASTER 1           
BARD_SKALD 1           
DRUID_AES_DANA 1           
DRUID_SHAPESHIFTER 1           
DRUID_AVENGER 1           
CLERIC_BANE 1           
CLERIC_TEMPUS 1           
CLERIC_SELUNE 1           
ABJURER    1           
CONJURER   1           
DIVINER    1           
ENCHANTER  1           
ILLUSIONIST 1           
INVOKER    1           
NECROMANCER 1           
TRANSMUTER 1           
WILDMAGE   1           
BARBARIAN  1