Broadsword Online Games released Publish 98 for Ultima Online on the Test Center shard back on July 24th of this year:

We are pleased to announce that Publish 98 will be available for testing on TC1 by 2pm ET July 24, 2017. Publish 98 is full of new features, so make sure you patch up your client and head over to TC1 to check out the latest update. Please note that some features will not be available on TC1, check the notes for full release details.

See you in Britannia

Since then, they have also released a small update for the Publish:

We have updated TC1 with the latest build of Publish 98 to include the following,

• Resolved issue where non-exploited pets were being flagged incorrectly for stat reverts.
• Increased spawn in Sorcerer’s Dungeon for Treasures of Halloween event.

Players are encouraged to transfer fresh copies of their pets to TC1 to verify the pet fixes, and to once again battle the Pumpkin King to test the new spawn rate. Please be sure to catch us on TC1 or send in your feedback.

Publish 98 will, as indicated above, bring this year’s Halloween content to the game, and also appears to bring additional enhancements to pet-related systems in Ultima Online. The Publish also includes the various player rewards and treasures that have been created to celebrate UO’s 20th anniversary, which will take place in September.