使用包含2个浮点数的元素序列定义XML模式

Question

I'm trying to define a schema for XML-files like this:

<?xml version="1.0" encoding="UTF-8" ?>
<traverse xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="test.xsd">
  <cp>1.0 2.0</cp>
  <cp>3.0 -2.0</cp>
  <cp>-1.365575 0</cp>
  <cp>4 1.3</cp>
</traverse>

It has to be a sequence of at least 3 cp's (control points) each defined by two doubles. I tried this (without the constraint that there have to be at least 3 control points):

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
  <xs:element name="traverse">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="cp" type="control-point" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="listOfValues">
    <xs:list itemType="xs:double"/>
  </xs:simpleType>
  <xs:simpleType name="control-point">
    <xs:restriction base="listOfValues">
      <xs:length value="2"/>
    </xs:restriction>
  </xs:simpleType>
</xs:schema>

When I try to validate the XML-file above, XMLSpy tells me that cp-tags arent't allowed inside the traverse-tag. Can anyone help me? Thanks!

Answer 1

Change this:

  <xs:sequence>
    <xs:element name="cp" type="control-point" />
  </xs:sequence>

to this:

  <xs:sequence>
    <xs:element name="cp" type="control-point" minOccurs="3" maxOccurs="unbounded"/>
  </xs:sequence>