[Koha] Newbie: MARC Framework editing question

[Johannes Graumann]

Hi,

Please bear with my ignorance ... I have created a noe MARC framework 
(BOOKS) and also an authorized value "Languages". The framework is derived 
from the Default framework and accordingly has a field "041 - LANGUAGE 
CODE". I proceeded to have that mandatory and linked it to the created 
authorized value.

My question now is: how does this actually work when importing something via 
z39.50 from let's say the LOC ... it's possible that MARC field definitions 
from souces conflict with my local setup. How are conflicts handled? Is it 
safer to generate a new (local) field rather than editing like done above?

Thanks for any hints.

Sincerely, Joh