This attribute is only a placeholder so that all the ISM attributes are not shown
in the schemaGuide for every element. If you refer to the documentation of the
attribute group it will say what attributes should be here.
Source
<xs:element name="publisher" type="contactInfoType"><xs:annotation><xs:appinfo><mdr:definition>This category is used to tag the identification of the entity responsible for releasing the data asset—the entity primarily responsible for the intellectual content of the product. It is intended that this category apply whenever applicable to an organization, as opposed to a person. Typically, the name of a Publisher should be used to indicate the organization, agency, or domain responsible for the resource. See also, DDMS Version 3.0 Publisher.</mdr:definition></xs:appinfo></xs:annotation></xs:element>