During a more detail discussion about the long term maintenance, WMDA DD technique group - XSD group comes up to the following update strategies from now on:

1. XSD main version like 2.1 and 2.2, will be updated yearly, Q4 is preferred
   Check the XSD update timeline based on known RFCs and other request in DD member public page
   https://share.wmda.info/x/GIt0Ew
2. Small changes that have no effect to the structure are possible to be arranged quarterly with version number like 2.2.1, 2.2.2
3. WMDA data upload system will always support 2 XSD versions
4. XSD transition period is one year for organizations, refer link in item 1 to check the update and retirement schedule.