Kindle Fixed Layout Tutorial - Part 5

This is the primary control center for your ebook, where the
features that effect the entire book are set, a detailed description is given,
and all its content is listed. Thus, it is often named content.opf, although as mentioned it can be called anything, such
as package.opf, which is fairly
common, or the title of the book, such as Amazon's own Guide.opf. I find it easiest just to keep the name consistent from
project to project as content.opf so
that I don't have to remember what it's called when I go looking for it. You
will be accessing this file many times and often throughout the creation
process.








OPF stands for open
packaging format, which refers to the specification that defines the
structure and semantics of the package, but essentially it contains a
descriptive listing of the ebook's physical contents; that is, the actual
component parts included in the archive, not its literary or artistic content.
It also provides some crucial information specifying how the Kindle will
display your pages.








This is the first of many files where we will need to explain
some things to the computer so it understands what we're saying and what to do
with the information that we give it.








The OPF consists of four essential sections, given in this
order:





      <Metadata>
      <Manifest>
      <Spine>
      <Guide>





Preceding these at the top of the page you'll see a few
lines that are standard coding declarations, stating what language we're
speaking (XML) and giving a namespace reference (xmlns), which is a specific
set of operating rules for the reading system to follow. In Kindle ebooks
currently the code is based on ePub 2.0, the standard laid out by the IDPF (the
International Digital Publishing Forum), which is what this declaration
specifies. You will find similar instances in the NCX and at the top of every
HTML file.








The only part you need to be aware of here is the very last
element, which is a "unique-identifier" that will be referenced in
the metadata section below, where it will be discussed further.











The first section of the OPF is where all the metadata for your ebook lives. Metadata
is "data about data," and in ebooks it provides all the information
about the book itself - its title, author, publication date, etc. - which is
used by libraries, retailers, search engines and other users to determine what
the book is and how to catalogue it. What you enter here will show up in
databases as diverse as your local independent bookstore or the Library of
Congress (or Copenhagen, or wherever it may wander in this worldwide market),
as well as Amazon and every other online ebook retailer you choose to
distribute to. The more metadata that you enter, the easier your ebook will be
found, and moreover, found by the readers who would most want to read it.








In addition to the standard metadata, Amazon has added its
own set of data attributes that determine several overarching functions of the
ebook that make the Kindle fixed layout format unique. These function for the
most part as on/off switches for various features, although a few have unique
values that will be explained in detail as we come to them.








Before we get to the metadata proper, however, we must
declare our data reference systems, of which we'll be using two. These you will
find on the first line of the metadata section:





      <metadata

         xmlns:dc="http://purl.org/dc/elements/1.1/"

         xmlns:opf="http://www.idpf.org/2007/opf">





The first of these, Dublin Core (dc), has provided
the primary set of fifteen metadata elements in use in ebooks for some time;
but the second, slightly newer Open Packaging
Format (opf) set, from the IDPF's own ePub spec, adds some specifics to
these that are useful for fine-tuning our statements, so we declare both here.








The general practice is to state the dc element followed by
an opf extension (if desired), such as this example for an ISBN:





      <dc:identifier
        opf:scheme="ISBN">ISBN#</dc:identifier>





where the generic Dublin Core identifier
is defined by the opf:scheme modifier
as an ISBN. The actual data is entered between the angle brackets: here as ISBN#, which you would, of course
replace with your own information, as will be the case for each metadata entry
in the general metadata section (Amazon's Kindle-specific system is slightly
different).








Technically, no opf modifiers are required, but their use
provides considerably more information, as you can see. And while not all
ebooks will include both, I have included them here for your reference, so that
you can use them if you choose.





<!-- A Note
Concerning Comments -->





Any text you see entered between angle brackets and dashes with
an exclamation point in front - such as those around the header above this
paragraph - is comment text, and is
disregarded by the operating system. It can consequently be deleted or altered
at your discretion. It is used to pass along useful notes or help to organize
the content. Here I have used it to create sections and sub-sections, and to
point out important elements. In css files forward slashes and asterisks are
used instead, like so:





      /* comment */




There the text also turns green, which is even
more helpful. But here in the opf everything is black and white.