cvc-datatype-valid.1.2.1：'mylns：xsi'不是'NCName'的有效值

Question

The Schema :

<xs:complexType>
  <xs:sequence>
    <xs:element ref="FileCreationList"/>
    <xs:element ref="DivestedExample"/>
  </xs:sequence>
  <xs:attribute name="mylns:xsi" type="xs:string"/>
  <xs:attribute name="xsi:schemaLocation" type="xs:string"/>
</xs:complexType>

The error:

Multiple annotations found at this line:
    - s4s-att-invalid-value: Invalid attribute value for 'name' in element 'attribute'. Recorded reason: cvc-datatype-valid.1.2.1: 'mylns:xsi' is not a valid 
     value for 'NCName'.
    - src-attribute.3.1: One of 'ref' or 'name' must be present in a local attribute declaration.
    - s4s-elt-invalid-content.1: The content of '#AnonType_File' is invalid. Element 'attribute' is invalid, misplaced, or occurs too often.

Answer 1

Attribute name declarations must be NCNames (non-colonized names):

 NCName ::= (Letter | '_') (NCNameChar)* /* An XML Name, minus the ":" */ 

Remove the colons from mylns:xsi and xsi:schemaLocation to eliminate the error.

Notes :

• Do not include a namespace prefix in an XSD declaration of an element or attribute name.

• Do not declare xsi:schemaLocation as an attribute in an XSD; declare and reference the http://www.w3.org/2001/XMLSchema-instance namespace:

   <root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.example.com/name try.xsd"/> 

Answer 2

Generally, if you want to declare an element that uses attributes in a different namespace, then you need to (a) declare those attributes in a separate XSD document, with a different targetNamespace, (b) use xs:import to import that XSD document, and (c) reference the attribute declarations using <xs:attribute ref="somens:localname"/> .

However:

(i) Namespace declarations (xmlns:xx="uri") are not considered to be attributes and do not need to be declared (indeed, must not be declared) in the schema

(ii) Attributes in the "xsi" namespace are special - they are automatically allowed on every element, and should not be declared in the schema.