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Package.CreateRelationship Method (Uri, TargetMode, String, String)

Creates a package-level relationship to a part with a given URI, target mode, relationship type, and identifier (ID).

Namespace:  System.IO.Packaging
Assembly:  WindowsBase (in WindowsBase.dll)

public PackageRelationship CreateRelationship(
	Uri targetUri,
	TargetMode targetMode,
	string relationshipType,
	string id


Type: System.Uri
The uniform resource identifier (URI) of the target part.
Type: System.IO.Packaging.TargetMode
Indicates if the target part is Internal or External to the package.
Type: System.String
A URI that uniquely defines the role of the relationship.
Type: System.String
A unique XML identifier.

Return Value

Type: System.IO.Packaging.PackageRelationship
The package-level relationship to the specified part.


targetUri or relationshipType is null.


The targetUri part is a PackageRelationship, or targetMode is Internal and targetUri is an absolute URI.


The value for targetMode is not valid.


The package is not open (Dispose or Close has been called).


The package is read-only.


id is not a valid XML identifier; or a part with the specified id already occurs in the package.

A package-level relationship defines an association between the package and an associated target part or resource. A package-level relationship can be one of two forms.

  • Between a Package to a target part in the package.

  • Between a Package to a target resource outside the package.

In a package-relationship the package is considered the "owner" of the relationship. When the package is deleted, all the relationships owned by the package are also deleted.

CreateRelationship does not physically change the target part or resource in any way.

The target of a relationship cannot be another relationship.

id must be a valid XML identifier. The id type is xsd:ID and must follow the naming conventions prescribed in the XML Schema Part 2: Datatypes specification (see

If id is specified as null a unique ID will be automatically generated. An id specified by an empty string is not valid.

If targetMode is specified as Internal, targetUri must be a relative URI that is formed according to the RFC 3986 Uniform Resource Identifier (URI) Generic Syntax specification. The internal relative URI can be either an absolute path that starts with a forward slash ("/") character such as "/page1.xaml" or "/images/picture4.jpg", or a relative path such as "../imagespicture1.jpg" that resolves against the package root ("/") as the base URI.

If targetMode is specified as External, targetUri can be either an absolute or relative URI formed according to the RFC 3986 Uniform Resource Identifier (URI) Generic Syntax specification. "" is an example of an absolute URI that references an external target resource "page2.xml". "images/picture1.jpg" is an example of a relative URI that also references an external target resource "1.jpg" but which resolves against the URI of the package itself.

relationshipType must be a URI that is formed according to the RFC 3986 Uniform Resource Identifier (URI) Generic Syntax specification. The following table shows the package-level relationshipType URIs defined by the Open Packaging Conventions (OPC) specification.

Package-level Relationship

Relationship Type URI

Core Properties data/core-properties

Digital Signature al-signature/signature

Digital Signature Certificate al-signature/certificate

Digital Signature Origin al-signature/origin

Thumbnail data/thumbnail

For additional information about packaging and package relationships, see section 1.3 of the Open Packaging Conventions (OPC) specification available for download at

The following example illustrates how to use CreateRelationship to create a PackageRelationship between a Package and a root document part. For the complete sample, see Writing a Package Sample.

// Add the Document part to the Package
PackagePart packagePartDocument =

// Copy the data to the Document Part
using (FileStream fileStream = new FileStream(
       documentPath, FileMode.Open, FileAccess.Read))
    CopyStream(fileStream, packagePartDocument.GetStream());
}// end:using(fileStream) - Close and dispose fileStream.

// Add a Package Relationship to the Document Part

.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.