Yes, they are called North American Routes (NARs)Are there definite tracks, ones that sort of match certain distances offshore for example and start down at the Boston/Moncton boundary and continue right up to east of Newfoundland?
The boundary between 132.70 and 127.12 is depicted on the chart. Aircraft that will just pass through a corner or small area of a sector are often handed off directly to the next sector. For example westbound flights heading to the USA over TOPPS will go from 132.70 directly to 134.95 even though they would be passing through 128.05 airspace initially (briefly). If that's what you are getting at ?I am thinking that there is a boundary between 132.7 and 127.125.