originally http://bugs.musicbrainz.org/ticket/5182 which asked for it as part of the release editor

Adding or altering ISRCs on the website has to be done on each individual track details page at the moment. This makes adding or fixing ISRCs for releases inefficient. It would be handy to have a way to supply this info on the 'Edit All' page where we have a complete overview of the tracks on a release. Ideally one shouldn't have to do this work manually but by some client application but I foresee a need for it when e.g. some release needs quite a bit of ISRC fixing.

Most people probably aren't interested in ISRCs. Because of that it would be better to not display the ISRc fields by default. Instead, a checkbox could be provided to toggle the display of the ISRC input fields on and off.