Catmandu::Fix::marc_set

    # Set a field in the leader
    if marc_match('LDR/6','c')
        marc_set('LDR/6','p')
    end
    # Set all the 650-p fields to 'test'
    marc_set('650p','test')
    # Set the 100-a subfield where indicator-1 is 3
    marc_set('100[3]a','Farquhar family.')
    # Copy data from another field in a subfield
    marc_set('100a','$.my.deep.field')

Read our Wiki pages at <https://github.com/LibreCat/Catmandu/wiki/Fixes> for a complete overview of the Fix language.

Catmandu::Fix