A new feature in MODX 2.2 allows Elements to define if tags in default property and property set values are pre-processed. This allows values provided to Elements in this way to use tags in values that are processed before being used by the Element, the same way it would be if the tags appeared directly in the Element tag string.
MODX Evolution’s Snippet Parameters were reinvented in Revolution as Element Properties: any Element can now have them, not just Snippets. And in addition, Property Sets. Groups of properties that any number of Elements can share, in a variety of ways. Cool, huh!?