The DAMAGE_TYPE_* constants are used in NWScript to indicate the damage type to which certain effects will apply or for which information will be gathered. This is a bit field, which allows constants to be combined with a bitwise-or (|), although in most cases this is not an option due to the nature of the commands accepting these constants.
|DAMAGE_TYPE_BASE_WEAPON||the damage type of the weapon wielded|
|DAMAGE_TYPE_NEGATIVE||negative energy damage|
|DAMAGE_TYPE_POSITIVE||positive energy damage|
There is also a special constant called AC_VS_DAMAGE_TYPE_ALL for use with armor class effects. This constant is the (bitwise-or) combination of the bludgeoning, piercing, slashing, and base weapon DAMAGE_TYPE_* constants (so it can be used wherever a combination of DAMAGE_TYPE_* constants is allowed).