[DoctorM]

In this case it is the Harry Potter novels. While the books all start with 'Harry Potter and the...', they are by no means alphabetical titles.

Apparently it does seem to be that 'Sort By Author' uses: Last Name, First Name, (I dunno about middle name/initial, but one would assume), (I'd also assume by book series name) and then by number in series.

Pretty cool. I checked an old Kindle 1 and it seems to do the same thing when sorting by author.

@dickloraine - The PRS-T1 also has 'Collections' which seems to work the sames as the 350's categories.

Edit: Tested Robert B. Parker's Spenser series and found the same thing. Sorting by Author groups the books together and in order of the series.

Testing more with the Kindle 1, apparently that sorts by Author and then file name. (e.g. 01 - Harry Potter and the Philosopher's Stone, etc.) The Sony just needs you to have set the series order in Calibre.