When you use the Recording edit page, existing ISRCs are displayed in text fields, allowing them to be edited:

However, editing the ISRC field does not generate a single edit. Instead it generates two separate edits, first an "Add ISRCs" edit which is applied immediately, then a "Remove ISRC" edit which is open for voting.

A suggestion to improve the form to clarify things would be to render existing ISRCs as non-editable links, with only a remove button. Clicking the remove button would indicate a pending deletion (e.g. strikethrough, faded) but not completely remove the row. Clicking the Add ISRC button would show a text field for entering a new ISRC.

Additionally, it would be good if ISRCs with pending edits would be highlighted, to reduce the chances of people submitting duplicate "Remove ISRC" edits.