1930 Mexican Census

In the Famly History Library Catalog, they have the 1930 Mexican census for
Guadalajara in several films numbered 1507525 thru 1507545. Each listing
reads: Censo 1930 (Leg.--) etc. Can anyone tell me what the Leg. stands
for? At my Family History Center, they couldn't answer that. I have never
checked these films before and do not know which one I should order. With
the U.S. census, I am familiar with enumeration districts being the way
cities were sectioned off for censusing. If you knew generally where
someone lived, you can check for them in the enumeration districts from that
location. How does it work with the Mexican census? I mean, if I know the
general area where my ancestors lived, how do I know which film it will be
covered in? I'm just very new at this and would appreciate being pointed in
the right direction.

Thanks,
Corrine Ardoin
Santa Maria, California