Why New Library Return Notice Naming Convention?

[SteveEisenberg]

Until a few weeks ago, Kindle Keyboard US public library return notices looked, in Windows Explorer, to give two real examples, like this:

Personal letter-asin_LoanExpired_B000XPPW50-type_PSNL-v_0.azw
Personal letter-asin_LoanExpired_B001HPW9OW-type_PSNL-v_0.azw

Then, approximately ten days ago, new ones started having humongously long file names which don't hint at what's inside. Here's one real example:

Personal letter-asin_PSNL!KICSGurupaUS!bGlicmFyeS1leHBpcmU_aWQ9QVd MT05OQ1lXNkdVRSZtYXJrZXRwbGFjZT1BVFZQREtJS1gwREVSJ mFzaW49QjAwNENGQVdVQyZlbmR0aW1lPTEzMzUyMjkwMTM2NzI-type_PSNL-v_0.azw

Comment:

Some Amazon customers who use Windows Explorer (or Linux and Mac equivalents) to manage their Kindle documents must now be confused, since the file name no longer tells you what the file is about. If you are one of those customers, I hope this post helps you a little. I think you can safely move, to a PC backup folder, any Kindle file whose name begins with:

Personal letter-asin_PSNL!KICSGurupaUS

Question:

Does anyone know why Amazon did this?

Less important comment:

Perhaps I should have put this in the Kindle Developers Corner area, since it does relate to my own programming. But past experience is that there isn't too much interest there in file naming, and, as explained above, there must be everyday Kindle users affected by this.

Thanks for all ideas!