StandardsRegExt xs vstd This is a core schema for describing IVOA Standards themselves. See complete specification at http://www.ivoa.net/Documents/latest/StandardsRegExt.html. a description of a standard specification. This typically refers to an IVOA standard but is not limited to such. the version of the standard that is recommended for use. More than one version can be listed, indicating that any of these versions are recognized as acceptable for use. a description and pointer to a schema document defined by this standard. This is most typically an XML Schema, but it need not be strictly. when present, this element indicates that all versions of the standard are considered deprecated by the publisher. The value is a human-readable explanation for the designation. The explanation should indicate if another standard should be preferred. a defined key associated with this standard. the IVOA status level of this version of the standard. For values of "rec", "pr", "wd", and "note", the record's referenceURL element should point to the official specification document in the IVOA Document Repository; if the document does not appear there, these values should not be used. an IVOA Recommendation an IVOA Proposed Recommendation an IVOA Working Draft an internal Working Draft of an IVOA Working Group a published IVOA Note not an IVOA standard or protostandard at this time. A designation of preference for the version compared to other versions in use. the most preferred version. Only one version should have this designation. a version whose use is now discouraged because a newer version is preferred. a description of a schema definition A URL pointing to a document that formally defines the schema. The document should be in a machine-parsable format when applicable. For example, when refering to an XML schema, the document should be an XML Schema or similar document that can be used to validate an instance document. A human-readable description of what the schema defines or is used for. A brief description--e.g. one statement--is recommended for display purposes. A URL pointing to a sample document that illustrates the use of the schema. When applicable (e.g. XML), the document should be in the format defined by the schema document. an identifier for the schema being described. Each instance of this attribute must be unique within the resourse description. For XML schemas, this should be the schema's namespace URI. Otherwise, it should be a unique label to distinguish it from other schemas described in the same resource description. a description of a standard service protocol. This typically refers to an IVOA standard but is not limited to such. an abstract description of one of the interfaces defined by this service standard. This element can provide details about the interface that apply to all implementations. Each interface element should specify a role with a value starting with "std:" or, if there is only one standard interface, is equal to "std". Applications that, for example, wish to build a GUI to the service on-the-fly would first access this generic description. Site-specific variations, such as supported optional arguments or site specific arguments, would be given in the actual implemented service description and overrides any common information found in this generic description. This generic interface description can be matched with the site-specific one using the role attribute. Even though the Interface type requires an accessURL child element, this element is intended to describe a service in the abstract--i.e. without reference to a particular installation of the service. Consequently, the accessURL may contain a bogus URL; applications should not expect it to be resolvable. A registered set of related keys. Each key can be uniquely identified by combining the IVOA identifier of this resource with the key name separated by the URI fragment delimiter, #, as in: ivoa-identifier#key-name the name and definition of a key--a named concept, feature, or property. The name and definition of a key--a named concept, feature, or property. This key can be identified via an IVOA identifier of the form ivo://authority/resource#name where name is the value of the child name element. This type can be extended if the key has other metadata associated with it. The property identifier which would appear as the fragment (string after the pound sign, #) in an IVOA identifier. A human-readable definition of this property. reference that forces an IVOA ID with a # fragment part appended to match the standard pattern for registering enumeration values with a vstd:StandardKeyList the allowed characters for a fragment identifier taken from rfc2396