XML Tutorial/XML Schema/maxLength

maxLength defines the maximum number of units of length using a nonnegative integer

<xsd:element name="myString">
  <xsd:simpleType>
   <xsd:restriction base="xsd:normalizedString">
    <xsd:maxLength value="10"/>
   </xsd:restriction>
  </xsd:simpleType>
</xsd:element>

To specify the maximum length of an element

File: Schema.xsd
<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  targetNamespace="http://www.wbex.ru" 
  xmlns="http://www.wbex.ru"
  elementFormDefault="qualified">
  <xsd:element name="description">
    <xsd:simpleType>
      <xsd:restriction base="xsd:string">
        <xsd:maxLength value="200" />
      </xsd:restriction>
    </xsd:simpleType>
  </xsd:element>
</xsd:schema>
 
File: Data.xml 
<?xml version="1.0"?>
<description xmlns="http://www.wbex.ru">test</description>