A schema (see What is an XML schema?) specifies the structure of an XML document and constraints on its content. Within the product, you specify the XML Schema that a diagram represents within the diagram’s definition. All items drawn on the diagram (elements, attributes, and so on) automatically report to this schema. XML artifacts that are not graphically drawn or represented on a diagram (such as Notations, External Entities, and Text Entities when generating DTDs) must be assigned the schema they represent within their definition properties. Once assigned, these non-graphical artifacts will be generated to a DTD when a diagram representing their schema is generated (the corollary is true on reversal of DTDs).
When you create a new XML Ddagram, you must specify the XML schema it will represent. In the diagram name dialog, click Choices for a list of existing schemas in the encyclopedia. If you are not sure of the name of the schema, type a temporary name, then go back later and change it to the appropriate name.
To rename an XML schema
1 Open the XML schema definition: Find it in the browser under Definitions, XML Schema, and then double‑click it or right-click it, and then click Open.
2 Change the schema’s name in its definition dialog (Dictionary Object - XML Schema), and then click OK. The schema name changes in all referenced definitions and diagrams.
Definition properties
System
The System field holds the location (path name or url) of the schema. For example:
http:// www.somedomain.com/product/file.dtd
The schema that is generated contains the SYSTEM keyword followed by the specified path and file name.
According to DTD specifications, the SYSTEM keyword is generally intended for private DTDs used by a single author or group.
Public Name
PUBLIC is an XML keyword indicating that the schema is intended for broad use. When the PUBLIC keyword is used, you must also specify a name for the schema.
If you want to use the PUBLIC identifier instead of the SYSTEM identifier, fill in the Public Name property. If the system sees a value in the Public Name field, the PUBLIC identifier is used instead of the SYSTEM identifier in the generated schema.
Comments
Text in the Comments field will be generated into the schema file but will be formatted as follows:
<!--your comments go here-->
Comments in the Definition tab are generated to the place in the schema where the schema is declared/defined.
Processing Instructions
Processing Instructions are passed to an application. They typically contain a declaration of the target application and whatever instructions the application needs to process the XML schema.
Text in the Processing Instructions field will be generated into the schema file but will be formatted as follows:
<?--your processing instructions go here-->
Processing Instructions in the Definition tab are generated to the place in the schema where the schema is declared/defined.
Description
Text in the Description field does not get generated to a DTD, but is generated to a BizTalk schema. You may enter a description of the modeling element, or its use in the schema. The description can be included in a report. By default, it is included in HTML reports.