My mandarin is not good enough to comprehend the discussions but from what I understand from a different source is what you possibly was alluding to is "moqi" which loosely translated is tacit understanding. If such "moqi" exist, it is inexplicable as to what happened with the recent incident which appears to be a coordinated event between the Chinese and the Russians to draw the Japanese into the contiguous zone as depicted by the pictorial timeline below.
View attachment 28458
When the three Russians military vessels entered the contiguous zone, it would be customary to escort them and that was what the Japanese destroyer Hatakaze did as Japan administers that area. When that happened , the Chinese Jiangkai waiting in the north then entered the zone which was then followed by the Japanese destroyer Setogiri. As such for a brief transit period there were six military vessels sailing in parallel to each other. The "moqi" is meant to avoid such situations because if there is any miscalculation the consequences would be greater than say with coast guard vessels.