previous is

operator

Return type: Switch
Returns:        Returns true if the previous element is the specified element, and false otherwise. Replacing is with isnt reverses the result.

Syntax
previous element-qualifier? (is | isnt) namespace-modifier? (element-name | element-name-list)
    


Purpose

previous is tests whether the previous sibling of the current element of the currently-active parse is an instance of the element element-name, or one of the elements listed in element-name-list. element-name-list is a parenthesized list of elements, separated by |. Replacing is with isnt will reverse these results.

If element-qualifier is not specified, the test applies to the previous sibling element of the current element. If element-qualifier is specified, the test applies to the previous sibling element of the element specified by element-qualifier.

You can specify the name dynamically by using the identity operator (~) followed by a string expression: for example, to check for elements with a previous sibling element of the same name as the current element,

  element #implied when previous is ~(name of element)
     suppress
          

The previous is test ignores inclusions and data content.