The <author> metadata element contains the name of the topic's author. The currently unsupported keyref attribute can point to another location where the author information is defined. The <source> element contains a reference to a resource from which the present topic is derived, either completely or in part. The element can contain a description of the resource; the href reference can be a string or a URL that points to it. The <publisher> metadata element contains the name of the person, company, or organization responsible for making the content or subject of the topic available. The <copyright> element is used for a single copyright entry. It includes the copyright years and the copyright holder. Multiple <copyright> statements are allowed. The <copyryear> element contains the copyright year as specified by the year attribute. The copyright holder (<copyrholder>) element names the entity that holds legal rights to the material contained in the topic. The <critdates> element contains the critical dates in a document life cycle, such as the creation date and multiple revision dates. The <revised> element in the prolog is used to maintain tracking dates that are important in a topic development cycle, such as the last modification date, the original availability date, and the expiration date. The <created> element specifies the document creation date using the date attribute. The <resourceid> element provides an identifier for applications that require them in a particular format, when the normal id attribute of the topic can't be used. Each resourceid entry should be unique. It is one of the metadata elements that can be included within the prolog of a topic, along with document tracking and product information, etc. The element has no content, but takes an id attribute or an appname attribute. The <audience> metadata element indicates, through the value of its type attribute, the intended audience for a topic. Since a topic can have multiple audiences, you can include multiple audience elements. For each audience you specify, you can identify the high-level task (job) they are trying to accomplish and the level of experience (experiencelevel) expected. The <category> element can represent any category by which a topic might be classified for retrieval or navigation; for example, the categories could be used to group topics in a generated navigation bar. Topics can belong to multiple categories. The <keywords> element contains a list of keyword entries (using indexterm or keyword markup) that can be used by a search engine. The <othermeta> element can be used to identify properties not otherwise included in <metadata> and assign name/content values to those properties. The name attribute identifies the property and the content attribute specifies the property's value. The values in this attribute are output as HTML metadata elements, and have no defined meaning for other possible outputs such as PDF. The <permissions> empty prolog element can indicate any preferred controls for access to a topic. Topics can be filtered based on the permissions element. This capability depends on your output formatting process. The <prodinfo> metadata element in the prolog contains information about the product or products that are the subject matter of the current topic. The <brand> element indicates the manufacturer or brand associated with the product described by the parent <prodinfo> element. The <series> metadata element contains information about the product series that the topic supports. The <platform> metadata element contains a description of the operating system and/or hardware related to the product being described by the <prodinfo> element. The <prognum> metadata element identifies the program number of the associated program product. This is typically an order number or a product tracking code that could be replaced by an order number when a product completes development. The <featnum> element contains the feature number of a product in the document metadata. The <component> element describes the component of the product that this topic is concerned with. For example, a product might be made up of many components, each of which is installable separately. Components might also be shared by several products so that the same component is available for installation with many products. This identification can be used to check cross-component dependencies when some components are installed, but not others. It could also be used to make sure that topics are hidden, removed, or flagged in some way when the component they describe isn't installed. Such process-control logic is not currently supported in DITA processing. The <prodname> metadata element contains the name of the product that is supported by the information in this topic. The <vrmlist> element contains a set of <vrm> elements for logging the version, release, and modification information for multiple products or versions of products to which the topic applies. The empty <vrm> element contains information about a single product's version, modification, and release, to which the current topic applies.