6a.
footnotes. z.m.l. handles footnotes just fine.
use brackets in the text to indicate a footnote. [_1_] there must be a space before the opening-bracket.
the text of the note should be placed in a section at the end of the document, where it should begin at the start of a line, and contain the exact same string-in-brackets as the indicator in the text. the string itself does not have to be a number; it can be anything you want. [_x_] for now, however, there cannot be a space inside of the footnote indicator.
whenever a footnote indicator occurs on a page, the footnote is placed at the bottom of the page. if the entire footnote will not fit at the bottom, an icon is presented which -- when clicked -- opens up the "workspace" and presents the text of the entire footnote there, along with the text of the other footnotes, in a scrolling-field that allows the user to view all of them together.
when the user gets to the section that contains
all the footnotes collected together -- which is
therefore essentially an end-note section --
the reverse of the process is put into play, so
a click on a note's text shows, in the workspace,
a scrolling-field that displays the text in the body
of the book where the footnote indicator is placed.
6b.
external links. one of the exciting things that turned people on to the web was the ability to click on "links" to jump to another place entirely; this was the experience of "surfing the web".
so one of the things that readers now expect from an e-book, even though "surfing" often isn't all that congruent with the reading of a book, is this ability to hotlink to an internet web-page.
so of course z.m.l. supports this type of linking, and does it with a method making it very simple: to link to a web-page, just put its u.r.l. in the text. for example, http://www.gutenberg.net would be an automatic link to the project gutenberg website.
you can also put a full u.r.l. in a footnote, and the
footnote indicator automatically becomes a link.
6c.
"internal" links. the z.m.l. viewer creates a rich set of "internal" links in the book, automatically, which serve to help the reader navigate the e-book.
specifically, each section header is a link "target", such that any place in the text with the same text as a section header automatically links to that header.
so, for instance, if you have a "chapter 6" section -- i.e., a section with a first line of "chapter 6" -- any place where the phrase "chapter 6" appears automatically becomes a link to that section; if the user clicks it, they'll be taken to chapter 6.
for a 2-part header -- where the parts are separated by a double-dash -- either part becomes a hot-link.
this can make a very nifty e-book, chock-full of links. sometimes it can become overzealous, too, such as when you have a section that is labeled "introduction", in which case unrelated uses of the word "introduction" would become links, which is not what you really want (even if it doesn't hurt anything, either, not really.)
still, keep this in mind when you make your headers. with creativity, you can make it work like you want. (these hotlinks are case-sensitive, which helps to minimize the occurrences of such "mistaken identity".)
but used strategically, these automatic internal links can help you create a tremendously powerful e-book.