An Additional Insured Endorsement that is triggered by a written contract. The AI Endorsement wording is identical to what you would get with a Scheduled Endorsement except for the following type of wording for the name of the AI and the Location of the work, "All persons or organizations where required by written contract.", "All Projects". There are variations to these wordings but they boil down to the same thing. This is the current default method of obtaining Additional Insured status.