There's no perceived line except in Indian propaganda.
The only agreed border line is the 1959/1960 border line by both countries.
All the 1993, 1996 and others from last decade and this decade agreements are "peace" agreements, not new border line agreements.
Only Indians have been imagining that new border agreements were signed in 1993, 1996, last decade and this decade but China never agreed to any new line. This is something that the Indian Government and the Indian military had been brainwashing Indians into believing and militarily quietly creeping onto Chinese side of the 1959/1960 agreed line.
China largly chose to ignore this sly but as a direct result of 5th August 2019, China is in the process of putting and end to this farce while Indian Government and Indian military is slowly but surely is withdrawing, surrendering and agreeing to the 1959/1960 status quo. Simply because India has no choice.