What does P.P.A. mean?

Question

I'm reading a book called Introduction to Algorithms, Fourth Edition, and I'd like to know what does the abbreviation "P.P.A." mean in the paragraph below?:

Julie Sussman, P.P.A., came to our rescue once again with her technical copy-editing under tremendous time pressure. If not for Julie, this book would be riddled with errors (or, let’s say, many more errors than it has) and would be far less readable. Julie, we will be forever indebted to you. Errors that remain are the responsibility of the authors (and probably were inserted after Julie read the material).

Observation: The text above was extracted from a book preface.

Answer 1

As detailed on the MIT Press site, it just seems to be an inside joke of sorts.

3. Get Julie Sussman, P.P.A., to copyedit your book. “P.P.A.” stands for “Professional Pain in the Ass,” and Julie is rightfully proud of the moniker. Julie wrote the Instructor’s Manual for our first edition, and she found so many errors in the book that we knew we had to get her to copyedit all subsequent editions. She has prevented us from embarrassing ourselves more times than I care to remember.

Answer 2

My best guess is that it was a joke by Sussman, a famous scientific editor, who used to hand out business cards saying 'Julie Sussman, P.P.A.'.

Thomas Cormen, co-author (with Charles Leiserson and Ronald Rivest), reflected in 2012 on Introduction to Algorithms (1990):

"[Y]ou would be surprised at how often people ask me the secret to writing a best-selling textbook. You would be surprised because it never happens. But if it did happen, here’s what I would say: "

No.3 on the list:

3. Get Julie Sussman, P.P.A., to copyedit your book. “P.P.A.” stands for “Professional Pain in the Ass,” and Julie is rightfully proud of the moniker. Julie wrote the Instructor’s Manual for our first edition, and she found so many errors in the book that we knew we had to get her to copyedit all subsequent editions. She has prevented us from embarrassing ourselves more times than I care to remember.

MIT Blog

A good editor is a strict and persistent one.