Ah OK thanks...I was reading the basic ScenarioX rules and saw this bit;
'The word ‘or’ between types means any combination of the two types may be used. If types are grouped by brackets all units in the brackets must be used if any are used. ‘(G)’ means a general is attached to this unit.'
It was the interpretation of the phrase 'any combination of the two types' that was worrying me and I wasn't sure how it interacted with the options.