An Extensible Markup Language (XML) schema was developed as a means of defining and describing a structure for capturing spacecraft command-definition and tracking information in a single location in a form readable by both engineers and software used to generate software for flight and ground systems. A structure defined within this schema is then used as the basis for creating an XML file that contains command definitions. The schema is divided into three sections:
- Header information, including information about the project and XML file to be derived from the schema;
- Project-specific definitions of types, roles, and allowable values of data; and
- The information necessary for defining the command structure, including the information necessary for generating all pertinent software.
Among the advantages afforded by XML for such applications are the following:
- There exist commercial off-the-shelf (COTS) software tools and standard scripting-language modules for parsing XML schemata. These tools and modules facilitate the ingestion of XML files for use.
- By use of COTS software tools, the structures of, and some properties of the data in, XML files can be validated against their parent XML schemata to detect errors early.