Let's now show how to specify child nodes of an element and how to write
the X-script of elements. The X-script of an element must be written in
the special attribute “xd:script” (the prefix "xd" must correspond
to the namespace of X-definition:
"http://www.xdef.org/xdef/4.2").
In the example below we added the child elements "Title" and
"Author". Both child elements contain a required text node. The value
of the text node is described by the element "xd:script". We consider
there are books with one author, more authors, or even without an author.
Therefore the quantifier of the element "Author" is specified as
"occurs *" (i.e. none or more occurrences) in the X-script of the element
model. However, the child element "Title" must be one (i.e. it is required):
<Book isbn="required int(10000000, 999999999);" published="optional gYear();" > <Author xd:script="occurs *;" > <xd:text> required string(); /* name of author */" </xd:text> </Author> <Title xd:script="required;" > <xd:text> required string(); /* title of the book */" </xd:text> </Title> </Book>
Since the default value of quantifier is "required" notice that the specification of such quantifier can be omitted:
<Book isbn="int(0, 9999999999);" published="optional gYear();" > <Author xd:script="occurs *;" > <xd:text> string(); </xd:text> </Author> <Title> <xd:text> string(); </xd:text> </Title> </Book>
Prev | Content | Next |