Untrained skill check

An untrained skill check occurs when a character uses a skill in which the character has no ranks. Not all skills allowed untrained checks; those that do not are marked as either "Requires Training: yes" or "Untrained: No". (NWNWiki uses the former.)

Buying a rank in a skill that requires training can be useful, even in cross-class skills. For example, a character with 16 Dexterity and no ranks in Open Lock is unable to pick a lock. If the same character buys a single rank in Open Lock, the character is able to attempt to pick locks with a +4 modifier, and is able to use Thieves%27 Tools.