Summary: Insurance Services Office (ISO) has a large number of standard endorsements to modify the commercial general liability (CGL) coverage forms in many significant ways; the endorsements help tailor the policy to suit underwriting requirements or to more closely meet the coverage needs of insureds in a wide variety of circumstances. The titles of most of these endorsements indicate their intent. And, the numbering of the endorsements is also instructive. For example, a general liability endorsement beginning with the numbers 20 means an additional insured endorsement; an endorsement with the beginning numbers 21 means an exclusion; 22 means special provisions for certain type of risks; and 99 is used for miscellaneous endorsements.