[ATDrake]

Originally Posted by Wendy Wolfe

Re: line drawings. We have been considering using dots, dashes, and/or heavier lines in lieu of color. The challenge we are having is that the schematics become significantly less "readable". Small, important details tend to get lost.

Another possibility that you might like to consider is using something like the "hatching" system that heraldry used before colour printing was common, much less cheap. Here's a Wikipedia article on it, and for an example of how it would look, alongside volunteer re-coloured equivalents without the hatching, Project Gutenberg's The Handbook to English Heraldry by Charles Boutell is pretty good at giving a taste (although some of the re-colourings are re-constructed from knowledge of what the colours would have been, where the original text shows them as plain drawings without the hatchings). And many of the old-school public domain heraldry books available for free via the Internet Archive use it as well, some of them representing very complex heraldic designs.

Potentially a hybrid approach, with hatchings or half-tone dots or whatever done in coloured lines which would show up well on a colour display but degrade gracefully to monochrome, could work, if it doesn't look too cluttery for the diagrams and thereby obscure them.

Originally Posted by Wendy Wolfe

Is it considered horribly bad form to go with three- or four-color? On Amzn, is it possible to warn in the book pre-purchase description that it requires a color screen? We aren't thrilled at the idea of requiring a color display, but it might be a compromise we have to make.

No, it's fine to go with colour if it seems like the best option. Quite frankly, MR skews towards e-ink reader owners, but likely most people outside are e-reading on some sort of phone/tablet/computer.

In the Amazon listings, it's certainly possible to auto-warn for large images/complex layouts, and even require a certain level of compatible device in order to even get the book at all. Here are some examples of free e-books which do just that, and perhaps you might like to try them out to see what kind of features they seem to be making use of: Scotland's Marine Atlas, The New Colombia, The 50 Ideas That Shaped Business Today, Highlighting Japan July 2014, Wine Regions of Victoria, South Australian Food User's Guide

Perhaps one might not be able to auto-warn specifically for colour, but there's always the option of placing a note very prominently at the top of the blurb description and the front of the e-book which people would be reading the sample of.

Originally Posted by Wendy Wolfe

I'll play with the idea of using typography in lieu of highlights. My other option is a table, where the front/back/common values have separate columns.

Actually, tables are starting to sound like a better idea to me, since it seems like the measurements used are things which would vary as one adapted the pattern to personal use. And so it might be nice to have them laid out kind of like a fill-in grid that people could copy to their own notes and substitute their own numbers for.

Originally Posted by Wendy Wolfe

Re: ecosystem barriers. In order to sideload to Kindle iOS devices, my understanding is that I have to downshift to an older MOBI format & lose significant formatting features. Am I incorrect on the details?

I really wouldn't know about this, but if you've got an iDevice handy, you can use Amazon's Kindle Previewer application to convert your experiments for sideloading and see if you lose any features you really wanted to make use of.