The Deadlands Classic rulebook says that if an aptitude lists concentrations then you must choose one, and that for 3 points you can choose an additional concentration.
The sample character given makes it clear that Shootin' concentrations all end up with the same score as the base aptitude.
But then a complication arises: Professional concentrations are all treated like distinct aptitudes and have their own score. It would be simple enough to assume that the usual concentration rules apply to most aptitudes, but Professional concentrations have a different system.
But then Languages are implied to work as distinct aptitudes too, but the rulebook doesn't explicitly say this.
And what about Academia? Should each concentration be a unique aptitude like Professional, or should it be like Shootin'?
And what about Fightin'? I assumed it should be like Shootin', but then the official character sheet gives space to put scores next to each concentration, much like it does for Professional.