Anything can be considered a textbook as long as you follow the rules for textbooks found in the help docs:

No writing or highlighting or underlining on text pages

• a signature or note on the flyleaf or inside front or back cover is OKAY
• an author's signature on the title page is OKAY
• writing or highlighting or underlining on the text pages is NOT OKAY
  • Exception: if it is a textbook or workbook, these are expected to have highlighting/underlining/writing
    • if you post a textbook/workbook, the condition must be described to the requestor in a Personal Message
    • AND the described condition MUST BE AGREED TO in a reply PM before the book is sent
    •  This is the one of the ONLY three cases in which a PM exchange about a book is required before the book can be sent (the others are for travel guidebooks and cookbooks--see below).

Yes, when the book is ordered, just PM with a description of the writing, and wait for a response to see if the other person wants to accept the book with the writing. If they do not want it, you would have to cancel the order.

If you search the help docs for the word "textbook", there's a "What is the definition a textbook" doc that goes through the logic of why it doesn't matter how we define a textbook.

A link to the PBS definition of textbook.

To answer your question...regardless of the actual book title, if you've used it as a textbook it's postable.  BUT only IF the required guidelines are followed (posted above by sassy).

Thanks for info.