SOKOJ (Serbian rights owner) works with ISWC Network and provides works to them, their agency code is 064. MusicBrainz still doesn't have SOKOJ ID as a possible work attribute.

Examples of works with SOKOJ IDs:

• T-903.784.534-4 (SOKOJ ID: 00007189684)
• T-903.802.767-7 (SOKOJ ID: 00039472171)
• T-903.784.160-4 (SOKOJ ID: 00024834884)
• T-915.095.873-9 (SOKOJ ID: 00003232741)
• T-910.774.051-2 (SOKOJ ID: 00004568004)