![](/images/new-backgrounds/1214202/214202161x1.webp)
Chapter 2 Building an XML model
KeyRef general properties
The General page of a keyRef property sheet displays the following properties:
Property | Description |
Name | Name of the keyRef constraint. It must be a |
| (See Glossary) |
Code | Code of the keyRef constraint. It must be a |
Comment | Descriptive label of the keyRef constraint |
Stereotype | |
| without changing its structure. It can be predefined or user- |
| defined |
ID | ID of the keyRef constraint. Its value must be of type ID and |
| unique within the model containing the keyRef constraint |
Reference | Name of a key or a unique constraint defined in the current |
| model (or another model with a specified namespace). The |
| Reference value must be a qualified name (See Glossary) |
Selector (XPath) | An XML Path Language expression that selects a set of |
| elements across which the values specified in the Fields page |
| must be unique. There must be one and only one selector |
|
|
For more information on Selector or XPath, see section Defining an identity constraint selector.
KeyRef fields properties
The Fields page of a keyRef property sheet displays a list of XPath expressions.
If there is more than one field (or XPath expression), the combination of fields must be unique.
For information on XPath expressions, see section Defining an identity constraint selector.
Creating an identity constraint
You create an identity constraint from an element property sheet.
XSM User's Guide | 69 |