Here is the entire paragraph as it is in 90.1 - 2007 SI edition:
G3.1.1 Baseline HVAC System Type and Description. HVAC systems in the baseline building design shall be based on usage, number of floors, conditioned floor area, and heating
source as specified in Table G3.1.1A and shall conform with the system descriptions in Table G3.1.1B. For systems 1, 2, 3, and 4, each thermal block shall be modeled with its own HVAC system. For systems 5, 6, 7, and 8, each floor shall be
modeled with a separate HVAC system. Floors with identical thermal blocks can be grouped for modeling purposes.
Exceptions: d. For laboratory spaces with a minimum of 2400 L/sof exhaust, use system type 5 or 7 that reduce the
exhaust and makeup air volume to 50% of design values during unoccupied periods. For all-electric buildings, the heating shall be electric resistance.
To me, the piece about 'heating shall be electric resistance' implies that you use system 8 instead of system 7, as system 7 uses Hot-water fossil fuel boiler by definition, while system 8 uses electric resistance heat.
I guess you could also interpret this very literally and say that it should be system 7 but with electric heating coils, but then this would no longer be system 7.