ARTICLE B15 ‑ DURATION
B15.01 The block rules shall be subject to revision by agreement between the Union and the Company.
B15.02 The Union or the Company may re‑open the block rules for discussion at any time by written notice.
B15.03 Where notice to re‑open the block rules for discussion is provided and no agreement can be reached, the block rules shall continue in full force and effect.
B15.04 In view of the nature of the block rules, it is recognized that matters which involve substantial additional cost should normally be considered in general negotiations for the renewal of the Collective Agreement, while procedural changes should normally be discussed at other times.