A previously view restricted Chrome issue reveals a Nexus 5 running an Android version with build string KTU65. The issue was first labeled as ‘Google Restrict View’ indicating it should only be visible to Google employees. Later the label was removed, revealing the not previously seen KTU65 build to everyone.
The presence of this build could indicate we’ll be seeing more Kitkat releases before Google moves on to e.g Android 5.0.
According to the convention the first letter is the codename of the release family (e.g. ‘K’ for Kitkat) The second letter is a branch code that allows Google to identify the exact code branch that the build was made from, and ‘R’ is by convention the primary release branch. The next letter and two digits are a date code. The letter counts quarters, with ‘A’ being Q1 2009. Therefore, ‘F’ is Q2 2010. The two digits count days within the quarter, so F85 is June 24th, 2010. Finally, the last letter identifies individual versions related to the same date code, sequentially starting with ‘A'; ‘A’ is actually implicit and usually omitted for brevity.
If we take the build string KTU65, the codename starts with the expected ‘K’, for Kitkat the second letter is a ‘T’, although Google has used many different letters in that position. The ‘U’ and the numbers next to it should identify the quarter, and as expected ‘U’ is Q1 2014. The 65 means the 65th day of Q1 2014 which makes it the 6th of March 2014 which means a relative new Android build.