With today's Steam update, items in the Steam Workshop can now contain data about compatibility with past versions of the game. Once this feature is enabled by the game's developer, mod authors can specify the versions of a game that are known to work for current and historical versions of a Workshop item.

This update to the Steam Workshop is designed to work in conjunction with a set of Steam APIs that game developers can use to manage historical versions of their game. For more information for game developers on game version management, please see our post New! Version Control For Steam Workshop Mods.

There are three main components of this update to Workshop:

1. Deliberate configuration by the game developer. First, it is important that the developer of the game is deliberate about their use of build branches and preserving past versions of the game. To do this, the game developer should keep past builds of the game as well-named branches and put them in a deliberate order. The developer should then also enable "Game Branch Versions" in the Workshop settings for the game. You'll know this is enabled when you see it listed as a feature in the workshop info.
   

2. Uploading multiple simultaneous mod versions of the same item. Steam Workshop mods have long supported version history, allowing authors to roll a mod back to a previously uploaded version if they need to. This new update allows the notion of two or more versions of an item being made accessible to players simultaneously.

3. Specifying the range of game versions that each mod version supports. In order to support multiple versions being accessible to players, Workshop item versions can now specify a range of one or more game builds that the mod author knows is supported by the mod. If no range is specified, Steam will assume the version works with any build of the game. If more than one version of the Workshop item are indicated as compatible with the player's current version of the game, then the latest uploaded version of the item will be the one that Steam downloads.

We know that many mod authors will not have the time to check whether their mod supports the latest version of a game. So we built this system to support ranges that include or exclude future updates. If the mod item is generally a simple item and likely to work with new versions of the game, then it may make sense to leave the supported range open-ended. However, if the mod is complex and the mod author wishes to test their mod with new game versions before declaring support, that can be easily done when configuring the supported ranges.

These settings can be viewed and configured under the 'Change Notes' tab for a Workshop item.

Note: Game developers can also configure their Workshop uploader tool to set supported versions when uploading or updating a Workshop item.

Q. I don't see the option to specify supported game versions for my Workshop creation. A. Make sure the developer of the game has set "Enable Game Branch Versions" in their Steamworks settings for the game. This is a signal that the developer has been deliberate in the ordering of their game versions.

Look for this icon under the 'Enabled Features' within the game's Steam Workshop 'About' page.