Validation of VO resource

An evaluation via a numeric grade that indicates the quality of the resource description, when applicable, to be used to indicate the confidence an end-user can put in the resource as part of a VO application or research study. Note that this is a relatively new IVOA standard and so not yet widely implemented for many resources.

Allowed Values:

• 0: The resource has a description that is stored in a registry. This level does not imply a compliant description.
• 1: In addition to meeting the level 0 definition, the resource description conforms syntactically to this standard and to the encoding scheme used.
• 2: In addition to meeting the level 1 definition, the resource description refers to an existing resource that has demonstrated to be functionally compliant. When the resource is a service, it is consider to exist and functionally compliant if use of the service accessURL responds without error when used as intended by the resource. If the service is a standard one, it must also demonstrate the response is syntactically compliant with the service standard in order to be considered functionally compliant. If the resource is not a service, then the ReferenceURL must be shown to return a document without error.
• 3: In addition to meeting the level 2 definition, the resource description has been inspected by a human and judged to comply semantically to this standard as well as meeting any additional minimum quality criteria (e.g., providing values for important but non-required metadata) set by the human inspector.
• 4: In addition to meeting the level 3 definition, the resource description meets additional quality criteria set by the human inspector and is therefore considered an excellent description of the resource. Consequently, the resource is expected to be operate well as part of a VO application or research study.