With Google's annual I/O developer conference around the corner, details are emerging of the products likely to be unveiled at the conference ahead of official announcements.

Google's next Android iteration dubbed "Android M" is likely to be introduced at the annual I/O event. Along with the Android M, Google will reportedly announce "a new update guarantee for Nexus devices", detailed information about which has been shared by AndroidPolice.

The Nexus devices will get major operating system updates for two years and security patches for three years since the release of the OS.

The security patches would be guaranteed for 18 months starting from the date of purchase of a Nexus device through the Google Store or the Play Store. The rule applies to both old and new Nexus devices.

According to the latest disclosure, the Nexus devices, which are already past their time frame, will not receive further software support. The Nexus 4, the Nexus 10 and the 2012 Nexus 7 model will not get the new Android M update, but receive the security updates for a while. There is some exception for the Nexus 7 2012, which is the oldest among the three.

The Nexus 4 and the Nexus 10, launched in November 2012, have crossed the two-year period for receiving the OS update. The Nexus 4, which was out of the Play Store in fall 2013, will get security patch until this fall.

The 10in Nexus tablet was sold for a little longer and out of the Play Store in fall last year, alongside the 2013 Nexus 7 model, which means the 10in tablet would get security updates until early next year.

As for the Nexus 7 2012 edition, the tablet was released in the summer of 2012 and dropped out of the Play Store after a year. While the tablet is already past the major update limit, it will get security updates through this summer only.

The 2013 Nexus 7 will enjoy system updates until later this summer and security patches through the summer of 2016.

The Nexus 5, introduced in October 2013, will get full OS updates until next fall, then security patches for a year.

The newer Nexus devices such as Nexus 6 and 9 are still on sale and are expected to receive system OTAs until next year fall.

Android M code name

Google is reportedly using an internal code name for Android M, called "Macadamia Nut Cookie" (MNC), which has appeared in AOSP as "mnc-dev". But the next Android version might not carry this name.

Google earlier used LMP, which stands for Lemon Meringue Pie and KLP for Key Lime Pie as internal code names for the Android versions, but the official release abandoned them in favour of Lollipop and KitKat. The same is expected to be applicable to MNC.

Check out the following links here and here to AOSP where there are mentions of mnc-dev.