$Attribute == $OtherAttribute
The double-equals (==) usage for tests of equality replace older use of a single equals sign.
Previously, a single equals sign acted as either an assignment of the right side to the left or as an equality operator, Tinderbox deciding which form to use depending on context. From v4.6 onwards, although a single equals sign may be used for an equality test the usage is deprecated and such legacy syntax support may be withdrawn in subsequent versions.