With these elements, it is possible to specify conditional rendering rules. Any number of <element> nodes are allowed as children. A dist attribute determines whether the immediately preceding or following element is tested (dist="1"), or the element to the left or right of the predecessor or successor (dist="2"). The value either tests both contexts. The default value for dist is 1.
Example 1: This rule renders a hyphen before each <g> tag, except when a <w> tag appears immediately to the left: