Citrix 7.15, or officially XenApp and XenDesktop 7.15 LTSR
In general, only medium to big companies use Citrix, and for these companies it’s not an option to upgrade their Citrix farm every 7 to 9 months. That’s when you use a LTSR, features are not updated, security and bug are. In the words of Citrix;
What is a Long Term Service Release of XenApp/XenDesktop/XenServer?
Long Term Service Release of XenApp/XenDesktop/XenServer is a benefit of Customer Success Services. Customers with Customer Success Services can opt to implement the Long Term Service Release of XenApp and XenDesktop or XenServer to receive 5 years of mainstream support and 5 years of extended support. In addition, by electing to implement a LTSR version, customers will receive fixes, known as a Cumulative Update. A Cumulative Update typically includes only fixes for the LTSR components without introducing new features and functionality that might impact the environment. Cumulative Updates are not considered version upgrades since they are typically void of new features and functionality. Rather, Cumulative Updates are maintenance updates to an existing product version. By opting to deploy an LTSR version of XenApp/XenDesktop/XenServer, customers can take comfort in knowing that they have longer cycles between version upgrades with minimal environment changes, which then lowers the long term IT management costs associated with their XenApp/XenDesktop/XenServer deployments.
Return of the local host cache, after being away for a long time the Local Host Cache is back
During a new installation of XenApp and XenDesktop, Local Host Cache is enabled by default. Connection leasing is disabled by default. After an upgrade, the Local Host Cache setting is unchanged. For example, if Local Host Cache was enabled in the earlier version, it remains enabled in the upgraded version. If Local Host Cache was disabled (or not supported) in the earlier version, it remains disabled in the upgraded version.
Improved session recording
Session recording allows you to record the screen session of every user that connects to your Citrix environment, new in 7.15 is experimental Load balancing for Session Recording.
There are other improvements, the full list can be found here; https://docs.citrix.com/en-us/xenapp-and-xendesktop/7-15-ltsr.html