1) COMB: COMB in ADJ -based combines with nouns referring to places to mean something positioned or existing mainly in the place mentioned, or operating or organized from that place.
...a Washington-based organization.
...American-based companies.2) COMB: COMB in ADJ -based combines with nouns to mean that the thing mentioned is a central part or feature.
...oil-based sauces.3) COMB: COMB in ADJ-GRADED -based combines with adverbs to mean having a particular kind of basis.
There are growing signs of more broadly-based popular unrest.
English dictionary. 2008.