Beginning with IBM i version 7.1, IBM has been issuing Technology Refreshes (for example, TR11 for the eleventh refresh). These are different from any other update method previously used by IBM for the i and its predecessors: the iSeries, System i or the AS/400. For some reason, they do not use the modification part of the version for this; all Technology Refresh levels remain at modification level zero (e.g. V7R1M0).
So if you have an IBM i running 7.1, how do you tell which is the latest TR that is installed on your system? Simply run the "Work with PTF Groups" command like this:
and look at the highest level installed. For 7.1, Level 11, released November 20, 2015, is the latest available with Level 12 coming soon. Here is a screen shot from an actual system showing Level 6 installed:
For a general introduction of Technology Refreshes for 7.1, 7.2 and 7.3, click here.
For the latest installed IBM i 7.2 Technology Refresh, use PTF SF99717. Level 5 was released November 11, 2016.
For the latest installed IBM i 7.3 Technology Refresh, use PTF SF99727. Level 1 was released November 11, 2016.
To install the latest TR, do not use the PTFs above. Use the PTFs in the IBM document in the link above. This document also shows you the marker PTFs you can look for.
Let me know through comments if you have any questions about this.
Updated May 23, 2015 to add information about Level 10 for 7.1 and Level 2 for 7.2.
Updated December 2, 2016 with the latest information.