Redmine

The term "principal" is only used in very few places within the user interface and is not really defined elsewhere. In the translations, the term is only used in the field_principal key.

About the only place where I came across this was as a validation error when trying to add a new project member and not selecting a user or group. Here, the error message is:

Principal can't be blank

As the term "Principal" is very obscure here, I propose we generally replace it with "User or Group".

In the German translations, things are worse because the term is currently translated there as "Auftraggeber" which actually means "client" in a strict business sense. Here, "Benutzer oder Gruppe" would be more appropriate as a direct translation of "User or Group".