Instance Tagging is a revamp of CollectionService which allows you to add multiple tags to any instance, to query what tags an instance has, and to enumerate all instances in the data model that have a given tag. The tags on each instance are serialized and replicated from server to client like any property would be.

We are planning on adding Studio UI for editing tags, but do not yet have anything. The goal is to make it easier for level builders and scripters to collaborate by making it so the level builders can tag objects like doors, death planes, and moving platforms so scripts can add behaviors to them. The current methods of tagging objects in this way are pretty disappointing, like using magic Name fields, magic StringValues (both of which are easy to typo), LinkedScripts, loader scripts, etc.

API: http://wiki.roblox.com/index.php?title=API:Class/CollectionService

Extras

There was a bug with this feature in a recent release where code that tried to find child objects named “Tags” would fail because of an unscriptable property. This has now been fixed.

Four new methods on Instance have been enabled:

You can now put constraints inside of GridLayout to change the CellSize.