I want to change the ringtone for many (thousands) of contact entries to "None" (or to a specific ringtone like the silent one I have). Multi-select in Contacts removes the "Edit" button. I tried adding multiple contacts to a new Group, thinking that might allow some bulk editing, but I could't find any additional controls.
Ringtone, texttone, and other fields seem to be non-standard and are not exported from Contacts, seemingly precluding bulk editing with an external program.
Here's a sample Contacts entry, which had manual editing of ringtone and texttone to "None", exported as .vcf (you can see no ringtone makes it to the file):
BEGIN:VCARD VERSION:3.0 PRODID:-//Apple Inc.//Mac OS X 10.11.6//EN N:Smith;John;;; FN:John Smith ORG:Test\, Inc.; TEL;type=CELL;type=VOICE;type=pref:212-555-1212 UID:e1c7352c-e7d9-4b02-ab16-d2f0cc8697ac X-ABUID:E1C7352C-E7D9-4B02-AB16-D2F0CC8697AC:ABPerson END:VCARD