Defines a metadata value for the current content item revision in a workflow.
The wfUpdateMetaData function can be used only for updating custom metadata fields. You cannot use this function to update standard, predefined fields
Takes two parameters:
The first parameter is the name of the metadata field.
The second parameter is the value of the metadata field.
Defines "This is my comment." as the value of the Comments field:
<$wfUpdateMetaData("xComments", "This is my comment.")$>