rule tag defines any type of "rule,"
such as a theorem, axiom, lemma, rule of thumb, etc., that
is presented as a statement optionally accompanied by a proof or
examples. This tag is especially useful for mathematical texts.
This CNXML:
<rule type='theorem' id='pythag-rule'>
<title>Pythagorean Theorem</title>
<statement id='pythag-statement'>
<para id='pythag-para1'>
On a right triangle, the sum of the squares of
the sides equals the square of the hypotenuse.
</para>
</statement>
<proof id='pythag-proof'>
<para id='pythag-para2'>
Your favorite proof goes here.
</para>
</proof>
<example id="pythag-example">
<para id='pythag-para3'>
Take a right triangle whose sides are of length
3, 4, and 5. In this case the sum of the square
of the two shorter sides is 9+16=25. The square
of the hypotenuse is 25. So the theorem holds.
</para>
</example>
</rule>
Results in this display:
On a right triangle, the sum of the squares of the sides equals the square of the hypotenuse.
Your favorite proof goes here.
Take a right triangle whose sides are of length 3, 4, and 5. In this case the sum of the square of the two shorter sides is 9+16=25. The square of the hypotenuse is 25. So the theorem holds.
rule may contain an optional label tag.
Next, it may contain an optional title tag. Next, it must contain one or
more statement tags. Finally, rule may contain zero
or more proof tags and zero or more example tags in any order.