Many XSLT instructions contain special attributes that are interpreted as XPath expressions. These expression attributes are generally named select or test. For example, the xsl:for-each element contains a select attribute and the xsl:if element contains the test attribute.

Such attributes can be defined by XPath expressions. You can set the values for these attributes using drag and drop to the XSLT element in the XSLT pane (in XSLT View) or target pane (in Map View).

To set the value of an XSLT expression attribute using drag and drop from the source tree, drag a line from the desired node in the source tree to the desired XSLT element in the XSLT pane. A line appears connecting the source tree node to the XSLT element.

The appropriate expression attribute is inserted for the XSLT instruction in the source view. For example:

<xsl:if test="/ns0:PurchaseOrder/BillTo/Address/@country">

The preceding example code is formed by dragging the country attribute in the source schema to the xsl:if statement in the XSLT tree. The code causes the if condition to test for the presence of the country attribute in the source schema.