019$b has been a part of the BSMARC dialect of NORMARC for a long time, and Koha supports displaying values from this field, but now that it is suddenly a part of official NORMARC Koha probably needs at least a value builder for it too. Sigh... See: http://www.nb.no/fag/kompetansesenter/kunnskapsorganisering/dnk/normarc and specifically page 49 of this PDF: http://www.nb.no/content/download/13026/81592/version/1/file/Normarc2012-01-19felter.pdf
See bug 18984.