XML Tutorial/XML Schema/minLength

minLength and maxLength facets are the minimum and maximum number of units permitted for the data type

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
  targetNamespace="http://www.wbex.ru" 
  xmlns="http://www.wbex.ru"
  elementFormDefault="qualified">
  <xs:simpleType name="USA_LicensePlate">
    <xs:restriction base="xs:string">
      <xs:minLength value="1" />
      <xs:maxLength value="9" />
    </xs:restriction>
  </xs:simpleType>
</xs:schema>
Any of the following values would therefore be valid for an element declared to use the USA_LicensePlate datatype: 
<LicensePlate>123456789</LicensePlate>
<LicensePlate>1ABC123</LicensePlate>
<LicensePlate>ABC-1234</LicensePlate>
<LicensePlate>LICENSE42</LicensePlate>

minLength defines the minimum number of units of length using a nonnegative integer

<xsd:simpleType name="productCodeType">
  <xsd:restriction base="xsd:string">
   <xsd:minLength value="5"/>
  </xsd:restriction>
</xsd:simpleType>

To specify the minimum 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:minLength value="200" />
      </xsd:restriction>
    </xsd:simpleType>
  </xsd:element>
</xsd:schema>
 
File: Data.xml 
<description xmlns="http://www.wbex.ru"> test</description>