They're checked at check-ins

• Fingers, so to speak
• Passports, visas etc
• Cards that typically include names and photographs: Abbr
• Driver's licenses and such, briefly
• Unconscious parts
• Young people may carry fake ones
• What bouncers may check
• Bouncer's requests, briefly
• They're checked when young-looking people buy alcohol: Abbr

Wiktionary Word definitions in Wiktionary
n. (plural of id English)