How are key , keyref xml schema applied?

Question

XSD

<парковаться xmlns="http://parken.org" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  xsi:schemaLocation="http://parken.org parken.xsd">
    <машина номер="12341"/>
    <машина номер="258"/>
    <машина номер="12"/>
    <машина номер="4587"/>
    <парковка id="12">
        <парк>258</parkt>
        <парк>12</parkt>
    </парковка>
    <парковка id="1597">
        <парк>12341</parkt>
        <парк>4587</parkt>
    </парковка>
</парковаться>

based on this xml document, you need to draw up a scheme in which cars have different numbers, parking lots have different ids. Only one car can be parked in one parking lot, which is already known from the document, and each car is allowed to stand in only one parking lot at most. How to apply these restrictions with key keyref and unique. Here is my scheme what I could do next, I don’t know, Tell me?

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://parken.org" xmlns:tns="http://parken.org" elementFormDefault="qualified">
    <xs:element name="парковаться">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="машина" maxOccurs="unbounded">
                    <xs:complexType>
                        <xs:attribute name="номер" type="xs:positiveInteger"></xs:attribute>
                    </xs:complexType>
                    
                    <xs:key name="номерType">
                        <xs:selector xpath="tns:парковаться/tns:машина></xs:selector>
                        <xs:field xpath="@номер"></xs:field>
                    </xs:key>
                
                </xs:element>
                <xs:element name="парковка" maxOccurs="unbounded">
                    <xs:complexType>
                        <xs:sequence>
                            <xs:element name="парк" type="xs:positiveInteger" maxOccurs="unbounded"></xs:element>
                        </xs:sequence>
                        <xs:attribute name="id" type="xs:positiveInteger"></xs:attribute>
                    </xs:complexType>
                    
                    <xs:key name="idType">
                        <xs:selector xpath="tns:парковаться/tns:парковка"></xs:selector>
                        <xs:field xpath="@id"></xs:field>
                    </xs:key>
                    
                   <b> <xs:keyref refer="tns:номерType" name="номерRefType">
                        <xs:selector xpath="????"></xs:selector>
                        <xs:field xpath="?????"></xs:field>
                    </xs:keyref>    </b>                
                    
                </xs:element>
            </xs:sequence>
         </xs:complexType>
    </xs:element>

</xs:schema>

Answer 1

Based
those. there can't be more than one known car in the same parking lot (in the XML example above, it can)
XSD

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:tns="http://parken.org" targetNamespace="http://parken.org" elementFormDefault="qualified">
  <xs:element name="парковаться">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="машина" maxOccurs="unbounded">
          <xs:complexType>
            <xs:attribute name="номер" type="xs:string"/>
          </xs:complexType>
        </xs:element>
        <xs:element name="парковка" minOccurs="1" maxOccurs="unbounded">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="парк" type="xs:string" maxOccurs="1"/>
            </xs:sequence>
            <xs:attribute name="id" type="xs:string"/>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>

    <xs:key name="УникальностьМашин">
      <xs:selector xpath="tns:машина"/>
      <xs:field xpath="@номер"/>
    </xs:key>

    <xs:key name="УникальностьПарковок">
      <xs:selector xpath="tns:парковка"/>
      <xs:field xpath="@id"/>
    </xs:key>

    <xs:keyref name="МашинаНаПарковкеСуществует" refer="tns:УникальностьМашин">
      <xs:selector xpath="tns:парковка/tns:парк"/>
      <xs:field xpath="."/>
    </xs:keyref>

    <xs:key name="ОднаМашинаНаОднойПарковке">
      <xs:selector xpath="tns:парковка"/>
      <xs:field xpath="@id"/>
      <xs:field xpath="tns:парк"/>
    </xs:key>

  </xs:element>
</xs:schema>