Defining "Footprint" when the Building is on a slope

Our project is on a sloped site so the main entry (we call it "ground floor") in above another entry point where part of the building is embedded in the earth. As a result the exposed lower level might count towards the building footprint? If so, then does the rest of that level count as the "footprint" of the building? The lower level is almost in the same plane as the floor above but the majority of the slope facing side is exposed and houses some of the building's hidden functions. This lower floor forms a podium/terrace at the ground floor level, hence my reason for asking for clarification.