a. As used in this section:
"Base salary" means the salary provided pursuant to a salary guide or table and any amount provided pursuant to a salary increment, including any amount provided for longevity or length of service. It also shall include any other item agreed to by the parties, or any other item that was included in the base salary as understood by the parties in the prior contract. Base salary shall not include non-salary economic issues, pension and health and medical insurance costs.
"Non-salary economic issues" means any economic issue that is not included in the definition of base salary.