It's somewhat older information (2009-Oct-14) as it still talks of the old "Softimage Advanced", but this page
in the Knowledge Base seems to offer the answer:
1 Softimage license
A Softimage license allows you to run an interactive seat of Softimage (XSI.exe) and render from inside the Softimage interface. For rendering, Softimage uses all CPUs and all cores on the local machine.
Softimage can also use up to four (4) satellite CPUs for distributed tile rendering.
Note that you can use a Softimage license to run xsibatch.
5 Batch licenses
A Batch license allows you to do command-line rendering with xsibatch.exe.
xsibatch.exe can also use up to four (4) satellite CPUs for distributed tile rendering.
Apart from the name change (Softimage Advanced is no more, but the Network License of Softimage inherited its 5 batch licenses, see here
), I don't think this has changed:
Softimage license can be used to run xsibatch & 5 batch licenses can be used to run xsibatch.
Ergo (I think): 5 + 1 = 6.
But I can't say for certain, as I don't work for Autodesk...