[Koha-devel] meaning of mandatory subfields

Hello, regarding the issue of mandatory subfields. What does it mean that a certain subfield is mandatory? For example take ISBN. 020a is currently marked as mandatory. does it mean that (1) a is mandatory in the 020 field, or (2) 020 is mandatory in addition to a being mandatory in 020? Should we allow "not mandatory" fields that contain "mandatory" subfileds within those "not mandatory" fields? Or am I not knowing what I'm talking about (which could very much be true)? -- Ambrose Li Chinese Cultural Centre of Greater Toronto | http://www.cccgt.org/