Although legacy syntax may still be supported, all references to attributes—i.e to their values—in Action code should use a '$' prefix to the attribute name.
Long term users must note that either/both the left or right-hand expressions must begin with a '$'.
Since v4.6.0, Tinderbox has attempted to support legacy code usage alongside the new forms, but don't expect such support to continue. It is thus worth coming to an understanding of the different implications of $Attribute(path) and AttributeName(pattern). Indeed, AttributeName(pattern) is now deprecated for String/List/Set.contains("pattern").
Examples of $Attribute(path) usage: