[Koha-devel] meaning of mandatory subfields

[paul POULAIN]

Ambrose Li [CCCGT] a écrit:

>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)?
>
In MARC, you've FIELDS and SUBFIELD.
A field is, for example :
200$axxx$bttt$c126987

The subfields being $a, $b and $c in this case.

The 200 field can be mandatory (the "line" MUST exist), and some of the 
subfields inside the field may be mandatory or not.
For example :
200 =>  mandatory
$a => mandatory
$b => non mandatory
$c => non mandatory
$x => non mandatory.
The sample before is a "valid" field, as the missing subfield ($x) is 
non mandatory.

So, every combination can be possible (M/M, M/NM, NM/M, NM/NM. For NM 
field and M field it means : the field is not mandatory, but if present, 
this subfield MUST be present)
HTH
note that 1.3.x version does not deals perfectly with mandatory fields.

-- 
Paul POULAIN
Consultant indépendant en logiciels libres
responsable francophone de koha (SIBGB libre http://fr.koha.org)