From prc_inc_switch.nss (line 333-356) PRC 3.3g
// switch whether unlearning spells for spont casters at level up should go according to PnP or Bioware rules
// if on, will unlearn according to Bioware rules (e.g. as many as you want)
const string PRC_BIO_UNLEARN = "PRC_BIO_UNLEARN";
/** PRC_UNLEARN_SPELL_MAXNR
If PRC_BIO_UNLEARN is ON, you may want to restrict the nr of spells that a spontaneous caster
can unlearn to just a few spells ("normal" Bioware rules allow unlearning all spells at every level).
When PRC_UNLEARN_SPELL_MAXNR is set to (hopefully) a small value, the spontaneous caster
will still be able to unlearn spells at EVERY level up with no restrictions to the spell level that may
be unlearned, but the maximum nr of spells that can be unlearned are determined by the value on the switch
When PRC_UNLEARN_SPELL_MAXNR is not set and PRC_BIO_UNLEARN is ON, the spont caster
may unlearn as many spells as he wishes at every level up
If PRC_BIO_UNLEARN is Off, the maximum spell level that can be unlearned and the caster level
at which unlearning a spell becomes possible will be determined according to PnP rules. However,
you may want to give your spont casters more than one single spell to unlearn via this switch. If
PRC_UNLEARN_SPELL_MAXNR is set to a positive value, this is the nr of spells that the spontaneous
caster may unlearn (assuming he is allowed to unlearn at least one spell according to PnP rules). If
PRC_UNLEARN_SPELL_MAXNR is not set and PRC_BIO_UNLEARN is Off, unlearning spells goes
according to the exact PnP rules, e.g. at most one spell may be unlearned (at specific caster levels and
with restrictions on the maximum spell level that can be unlearned)
*/
// holds the maximum nr of spells that can be unlearned when the spont caster is entitled to unlearn at least one spell
const string PRC_UNLEARN_SPELL_MAXNR = "PRC_UNLEARN_SPELL_MAXNR";
