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maxOccurs depends on minOccurs

From: Ace <Ace@AceProgrammer.com>
Date: Tue, 11 Apr 2000 16:42:00 -0700
Message-ID: <38F3B848.BCBAF8C7@AceProgrammer.com>
To: www-xml-schema-comments@w3.org
I noticed that in the examples that are in XML Schema Part 0: Primer,
that the comment element is usually defined:

 <xsd:element ref="comment" minOccurs="0"/>

The Primer explicitly says this means the element is optional.  However,
after looking at the spec and the explanation in the Primer, it seems to
me that this actually makes the comment prohibited because it falls into
the third case below.  I hope I am mistaken.  I'd rather the above
syntax mean that the element is optional.


Nick K. Aghazarian


From section 4.3.2 of XML Schema Part 1: Structures:

the element element information item has complexType or group as an
ancestor and the ref [attribute] is present:

Particle Schema Component
Property            Representation
{min occurs}      The lexical [value] of the minOccurs [attribute], if
present, otherwise 1
{max occurs}     1. unbounded, if the maxOccurs [attribute] equals
                           2. otherwise the numeric lexical [value] of
the maxOccurs [attribute], if present,
                           3. otherwise the lexical [value] of the
minOccurs [attribute], if present,
                           4. otherwise 1.


From section 2.2 of XML Schema Part 0: Primer:

The comment element is optional within PurchaseOrderType because the
value of the minOccurs attribute in its declaration is 0. An element is
required to appear when the value of minOccurs is 1. The maximum number
of times an element may appear is determined by the value of a maxOccurs
attribute in its declaration.  This may be a positive integer value such
as 41, or the term unbounded to indicate there is no maximum number of
occurrences. The default value for minOccurs is 1, but there is no
default value for maxOccurs per se: When an element is declared without
a maxOccurs attribute, the maximum number of the element's occurrences
is equal to the value of the minOccurs attribute. If this value is also
omitted, the element must appear exactly once.

Received on Tuesday, 11 April 2000 19:44:57 UTC

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