Several different conventions exist for representing the three coordinates.
The four conventions still exist within the association and counted over 1100 member churches in 1995.
Certain international conventions exist in relation to the enforcement of awards against states.
Different conventions exist around the world for date and time representation, both written and spoken.
The national convention of advertisers doesn't exist as far as you're concerned.
Some conventions may be very regional practices, and thus may not exist in all regions of Japan.
Several different conventions exist for representing the three coordinates, and for the order in which they should be written.
Many modern mathematicians even hold that all convention, duty, morality, good, and the like, could not exist except for the fiction of free will.
Moreover, a few laws and conventions exist that limit the exercise of parliamentary sovereignty.
Some will object that international conventions exist on this very subject.