'correctness in deportment or behavior.'

Here it is means exactly what you say.

Common in French and in Dutch. Correctness in deportment or behaviour.
But both in French and in Dutch it also means correctness, straightforwardness of moral behavior. I often heard it used when French people were discussing some actions or decisions:

"Oui, voilà, mais ce n'est pas tout à fait comme il faut quandmême."
or in Dutch:
"Ja, maar dat is tòch niet helemaal comme il faut."

It may concern little business transactions, social conduct, politics and such.