while @hanno.klein already answered some of the PositionEffect-related questions and there are some posts in the history of the forum I did not find all answers.
We need to communicate to a trading system (e.g. Avaloq) that it should not round or reject very small orders because we want to close the position. So we send 77=C (CLOSE).
But what shall we send if we send a normal order and we do not know whether it opens a new position or just augments it. Is it 77=O (OPEN) or 77=D (DEFAULT) or …
Just leaving out the value is not an option because we want to design our trading interface accordingly and have to specify all enumerations.
Many thanks, Jörg