The map command controls how AWS decides to deal with requests for objects based on their URL. The format for a map command is:
map URL module arguments
Every request that comes into AWS is checked against each map command, in the order the map commands appear in the file. If the URL of the map is a prefix of the URL in the request, the request is passed to the named module, along with the arguments from the map command. The module may then provide the object, issue an error, or do nothing. In the first two cases, the request has been handled, and AWS closes the connection to the client. In the last case, AWS continues checking each map to see if there is one that can handle this request.
See the module documentation for details on using specific modules.