Mozilla has finally decided the User Agent string for its upcoming mobile operating system, Firefox OS, which was earlier named as Boot to Gecko (B2G). The UA string of Firefox OS will be free of operating system identifier.

Earlier, Mozilla developers had plans to include OS identifiers like “Android”, “Android like(b2g)” and “Gonk, like Android” to ensure maximum compatibility. But later they decided to remove OS token to avoid conflicts and future problems.

Mozilla’s Gervase Markham explains the reasons to omit the OS identifier, “Any OS identifier involving Android will lead to bugs like bug 777633 (serving of Android intents), the pushing of “install this Android app!” and other problems. Such problems will continually occur, and evangelising them is hard. UAs with Gonk or B2G as their OS identifier had the same content profile as UAs with no OS identifier at all.
Leaving out the OS means we don’t have to change UAs when we change OS in the future, meaning we have less evangelism to do later. Having it different from Fennec Android makes market share determination a little easier. And finally, having no OS identifier is a strong values statement of the web is the platform.”

The finally decided UA string of Firefox OS is as:

Mozilla/5.0 (Mobile; rv:14.0) Gecko/14.0 Firefox/14.0

The User Agent string is generally sent over every network request as a header field for identification, and usually include information like application’s name and version, operating system and platform, software vendor etc.

  (via Lawrence’s blog)