In this exercise, you will use the TEI pizza chef in order to make a special purpose XML dtd. You will need access to an internet browser such as IE5, Netscape, or Opera, and some experience of using Windows.
Our goal in this exercise is to make a very very simple DTD, which
we can use to mark up a multimedia document. We don't need anything
like the full complexity of TEI Lite, much less the full TEI. We just
want to mark up headings, dates, lists, paragraphs, figures and
... sound clips. Unfortunately, the TEI Guidelines don't seem to have
an element specifically for marking up sound clips, so we need to
invent it. While we are being imaginative, we will also add a
scale attribute to the existing TEI
<figure>
element.
Generate Local Modifications Files
(B) - by default we want to ignore all the elements.You will see a list of all the tags now available for inclusion
in your DTD. Click on any element name to see full information about
it. Check the first of the three tick boxes to the right if you want
to include the element in your dtd. For this exercise, we will need
only the following elements:
<body>
,
<date>
,
<div>
,
<head>
,
<item>
,
<list>
,
<note>
,
<p>
,
<respStmt>
,
<TEI.2>
,
<text>
, and
<title>
. In addition, we will need the
<figDesc>
element from the tagset for figures and tables.
Click on the Send me the TEI.extensions.ent file button. The
pizzaChef will now send you a TEI extension entity file. Depending on
your browser settings, you may see this displayed, or the browser may
ask if you want to save it. Either way, make sure you save it on your
local disk in text
format (do NOT save it as an HTML file!). Most browsers will try to
save the file under a name such as
myExtns_ent.txt, if you specify that the file is
to be saved in text format. Use the BACK button to
return
to the browser window (if it has expired from the cache you may have
to reload it)Although we want to use the
<figure>
element in this
exercise, we want to simplify its content model and add an
attribute. Find this element in the list and click on the third of the
three check boxes to indicate that you plan to modify it.Click on the Send me the TEI.extensions.dtd file button. The
pizzaChef will now send you a TEI extension DTD file, which you should
save on your local disk, in
the same way as before. Make sure to change the filename so that you
do not over-ride the entity file you saved earlier. Minimize the web browser window, and open the second of the two
files you have just received from the pizzachef using Wordpad, or the
editor of your choice. You will see that it contains the standard TEI
declaration for the
<figure>
element, which currently reads
<!ELEMENT figure - - (head?, p*, figDesc?, text?)> <!ATTLIST figure %a.global entity ENTITY #IMPLIED>Using the editor, change this declaration to read
<!ELEMENT figure - - (head?, figDesc)>
<!ATTLIST figure %a.global entity ENTITY #IMPLIED
scale CDATA "100">
and save the file.Since we also want to add a new element to the DTD, not defined
by the TEI, its declaration must be added to this same extensions.dtd
file. Type in the following declaration for the new element, and
save the DTD file again
<!ELEMENT soundClip - o (date) >
<!ATTLIST soundClip %a.global;
entity ENTITY #IMPLIED
duration CDATA #REQUIRED >
We are not quite finished. Simply declaring a new element does
not include it in the content model of any other element: the easiest
way of doing that is to include it in one of the TEI model classes,
which involves modifying the corresponding parameter entity in the
extensions.ent file. Open the exercise.ent file with your
editor.As you see, this file is mostly composed of "IGNORE"
declarations for the elements we are not using from our chosen
tagsets. To add the
<soundClip>
element to the
data class, simply type <!ENTITY % x.data
"soundClip|"> at the start of the file. (The space after the
percent sign, and the vertical bar are both essential!). Save the
fileOnce you're happy with your extensions files, it's time to send
them to the pizzachef. Open the browser window again. Press the Back
button to go back to the main pizzachef page, and scroll down to the
point where you are invited to specify the names of your extension
files. Use the browse button to locate first the extensions entity
file (it will probably have a name such as
myExtns_ent.txt) and next the extensions DTD file (it
will probably have a name such as myExtns_dtd.txt)
.Scroll down to Step 5, near the end of the page. Select option b
XML with no tag omissibility information. Press the
Generate full DTD button. The pizzachef will now send you
another file, which contains your compiled XML dtd. Save it under the
name myPizza.dtd. Congratulations! You have made
a valid XML dtd!Experiment with your DTD in your favouritte XML editor. If you
are using emacs, start by creating a new XML file. Type in the following two
lines at the start:<?xml version="1.0"?> <!DOCTYPE TEI.2 SYSTEM "myPizza.dtd">Go to the DTD menu and select the first option
parse DTD. You should now find that the Markup menu will
offer you only elements from your new DTD. You may wonder why your DTD contains more elements than you
specified above. The additional elements all come from the TEI Header.
This is because the TEI Header is a mandatory component of
every TEI document, so the current version of the pizza chef does not
allow you to modify it in any way. However, you should find that once
you start entering material into the
<body>
of your document,
the number of elements available to you is drastically
reduced.