The root of the extension is the expressions element. This contains a list of one or more autopopulate expressions to evaluate. A list of expressions An expression element represents one autopopulate XPath to evaluate. The expression element must occur in an expressions element.
  • Computed Expression: Yes
  • Legal Values: any XPath expression that returns an element or attribute node
  • Default Value: None
  • Inheritance rules: refer to ECHO Forms Specification section 4.5 XPath Context.

The ref attribute indicates which node in the instance the resolved metadata elements will be added to. In the example below it points to the granulesize element in the instance.

  • Computed Expression: Yes
  • Legal Values: any XPath expression into the catalog item metadata
  • Default Value: None
  • Inheritance rules: No inheritance

Metadata is an XPath expression that will be resolved against the metadata of a collection or granule. It can refer to a node, node set, or string value.