Relationship references define references between files and are located in special Common Services files with the file name extension “.rels”. The reference source is defined by the file name where the relationship definition is located. For the reference targets, the URI syntax is used. The reference targets can be internal or external to the Descriptor. This is denoted by the “TargetMode” attribute. Every relationship reference shall have a valid XML identifier of type xs:ID (see ISO/IEC 29500-2:2021 clause 6.5.3.4).

All Information  Model attachment and embedded Descriptors in a Descriptor shall be the target of a relationship reference, and all these files shall be reachable from the Root AML files via relationship references. The relationship references in a Descriptor shall form a Directed Acyclic Graph with the Root AML files as the starting points and with all Information Model, attachments, and embedded Descriptors in a Descriptor referenced from the Root AML files either directly or indirectly (i.e., over a chain of references). There shall be no circular dependencies between the files in a Descriptor. For more details, see IEC 62714-1.

For relationship references to a Descriptor, the Pack URI syntax shall be used to reference individual files in the container.

Some examples for relationship references:

• Example of an internal relationship reference from a file “configuration.AML” to a file “library.AML” (The relationship is contained in the file “configuration.AML.rels”):

<Relationship Type=“http://schemas.automationml.org/container/relationship/Library” Target=“file:///library.AML” TargetMode=“Internal” Id=“R725e8e211760485b”/>

• The same example for an external relationship reference:

<Relationship Type=“http://schemas.automationml.org/container/relationship/Library” Target=“http://test.org/library.AML” TargetMode=“External” Id=“725e8e211760486b”/>

• Example of an internal relationship reference from a file “configuration.AML” to an attachment file “manual.pdf” (The relationship is contained in the file “configuration.AML.rels”):

<Relationship Type=“http://schemas.automationml.org/container/relationship/AnyContent” Target=“file:///attachments/manual.pdf” TargetMode=“Internal” Id=“725e8e211760486c”/>

• Example of an external relationship reference from a file “configuration.AML” to a Descriptor “SensorProduct.amlx” (The relationship is contained in the file “configuration.AML.rels”).

<Relationship Type=“http://schemas.automationml.org/container/relationship/AnyContent” Target=“http://vendor.org/SensorProduct.amlx” TargetMode=“External” Id=“R725e8e211760487b”/>

• Example of an external relationship reference from a file “configuration.AML” to a file contained in the Descriptor “SensorProduct.amlx” (The relationship is contained in the file “configuration.AML.rels”).

<Relationship Type=“http://schemas.automationml.org/container/relationship/AnyContent” Target=“pack://http%3c, ,vendor.org,SensorProduct.amlx/attachments/sensor.jpg”TargetMode=“External” Id=“R725e8e211760488b”/>