IP Code classifies and rates the degree of protection provided against the intrusion of solid objects, dust, accidental contact, and water in mechanical casings and with electrical enclosures. The standard aims to provide users more detailed information than vague marketing terms such as waterproof. The digits indicate conformity with the conditions summarized in the tables below. Where there is no protection rating with regard to one of the criteria, the digit is replaced with the letter X. For example, an electrical socket rated IP22 is protected against insertion of fingers and will not be damaged or become unsafe during a specified test in which it is exposed to vertically or nearly vertically dripping water. IP22 or 2X are typical minimum requirements for the design of electrical accessories for indoor use. While IP may not be something that indoor lighting requires, from the outdoor applications perspective, this could be the most important of tests for the lifetime of the fixture.