Thanks again for all your help and suggestions.
The author for whom I prepared the ePub version of his text book wants the mobi version to appear much the same as the print version - indents and all. So far as I can tell the only way I could do that is to prepare another version which will work around mobi's limitations. After completing a version based on valid XHTML 1.1 I'm not prepared to do the book all over again based on invalid HTML 3.2. So I'm going to suggest to the author that he sell the pdf version to those students who use Kindles.
I have downloaded the Amazon Kindle publishing guide just to have as a reference.