Comment # 6 from Marc Véron

I have implemented Ian Walls' suggestions #1-#3 on my server.

Preferences in Section "Checkout Policy" read like this:

2 Fields:
AgeRestrictionField AgeRestrictionSubField [   ] [   ] Marc field / subfield
for age restriction. E.g. 521 a (Empty AgeRestrictionField - Do not apply age
restriction) 

1 Field:
AgeRestrictionMarker [   ] E.g. FSK|PEGI|Age| (No white space near |). Entry in
Marc e.g. PEGI 6 (Empty - Do not apply age restriction)

1 Drop down list:
AgeRestrictionOverride [Prevent | Don't prevent] patrons from checking out an
item whose age restriction would apply.