legal bedrooms in Ma?

[Robert Granara]

im looking into a 3 family property...it is 3 1/2 stories...

the 3rd unit is a townhouse style unit (3rd & 4th floors) and it has 3 bedrooms and a bath on the 4th floor...there is one staircase from the kitchen up to the 4th floor

anyone know if these are legal bedrooms and what the ma code is for exit ways/egresses in townhouse style units like this?

and how would this be diffent from a regular townhouse unit or single family for that matter?