Uniqueness of effective variations

For each effective variation of a given project item, the combination of version signature and keyword signature must be unique. TestArchitect enforces that uniqueness when you create new variations.

Recall that a given explicit variation may be defined with multiple nodes of a given system, as well as complex keyterms – that is, ones having multiple OR'd keywords. TestArchitect factors such variations out to produce effective variations, each of which has only a single version node and no complex keyterms. So if, for example, should an explicit variation should be created with the following signature:
login {Car Rental: 1.1, 2.0} {Spanish|French, Home}
, we can regard that as equivalent to the following four variations:
login {Car Rental: 1.1} {Spanish, Home}
login {Car Rental: 2.0} {Spanish, Home}
login {Car Rental: 1.1} {French, Home}
login {Car Rental: 2.0} {French, Home}
Given this fact, the following variations are/are not allowed to coexist with the above variation:
Variation Allowed? Why?
login {Car Rental: 1.1} {Spanish} Yes A login effective variation with signature {Car Rental: 1.1}{Spanish} does not yet exist
login {Car Rental: 2.0} {Spanish, Home} No A login effective variation with this signature already exists
login {Car Rental: 2.0} Yes A login effective variation with system signature {Car Rental: 2.0} and no keyword signature does not yet exist.
login {Spanish, Home} Yes A login effective variation with keyword signature {Spanish, Home} and no system signature does not yet exist.
Note that if you attempt to create a variation which conflicts with an existing variation's signature, an error message is displayed: