Misunderstood case 1

I'm working on a project in an urban space that have Local Zoning Ordinance. In this Local Zoning Ordinance, it is written that 40% of the open space must be vegetated. Does it means that there is 'Open Space Requirements' or the 'Open Space Requirement' is only for the surface of the Open space? To my point of view, I'm situated in Case 3 because the Local Zoning Ordinance doesn't said anything about the size of the open space. If not, in the case 1, the 25% asked is for 'open space size' or 'vegetated open space size'? I hope my question is clear. Thanks in advance for your help.