[W]hen given their ordinary and common sense meaning, the words “gross earnings” are clear and unambiguous insofar as they indicate that vacation entitlement for regular part-time and casual employees shall not be based only on base wage rates but rather should include all monetary payments to employees, and while there may be disagreement as to whether a particular payment ought to be included in “gross earnings”, arbitration boards for the most part have determined that “gross earnings” includes most monetary payments.
(Bruyere Continuing Care and CUPE, Local 4540 (Burnett), Re (2016), 2016 CarswellOnt 633 (Ont. Arb.) at para. 33 Starkman (Member))