The duties (munera) were a communal obligation assumed by the municipes in exchange for the privileges and protections of citizenship.
No matter where a person lived, at home or abroad, or what his status or class, he was a citizen of the locality in which he was born.
This act removed the sovereignty and independence from the signatory local communities, replacing them with the jurisdiction of a common government.
The city of Romulus synoecised the nearby settlements of Latium, transferring their populations to the seven hills, where they resided in typically distinct neighbourhoods.
As it is unlikely that all the Sabines were invited to Rome, where facilities to feed and house them did not yet exist, it seems clear that population transfer was only offered to some.
The partial synoecism took the form of a charter granting incorporation into the city of Rome and defining the rights and responsibilities of the citizens.
Executive power in municipium was held by four annually elected officials, composed of two duumvirs and two aediles.