Here is a link to the latest in the series of Technical Briefing documents issued by the ICC: https://files-eu-prod.cms.commerce.dynamics.com/cms/api/tptqvzzsbg/binary/ME1lfj?pubver=none#msdynttrid=5vzWILedZl2HkB5aUkizF5KCqvdF2lSh-dQUuzTkMwM
Briefing No. 5 is on the subject of Modifications and Exclusions under Documentary Credits subject to UCP 600.