void
From NWN Lexicon
A null data type. Void-returning functions don't return an assignable value, but returning allows you to end the function early. Only functions of type 'void' can be assigned to the Action Queue.
[edit] Example
void SpeakWithPC(object oPC) { // Abort if oPC is not a PC if (!GetIsPC(oPC)) return; BeginConversation("", oPC); }