DD> Are Network Coordinators on 'zone:net/0's meant to run a BBS or message DD> base ?
no... but they can if they want to... they should have a minimal filebase, too, for things like the policy document and the network's news letter so they can at least be FREQed... it is a good idea for a /0 to run a bbs because that gives prospective members a place where they can go to ask questions and download documentation and applications and whathaveyou...
DD> Or do they just need to run a mailer that does nothing but hold DD> packets ?
in fidonet, all member systems must run a FTN mailer... that's the minumum requirement aside from having a mail tosser package to handle the mail... other networks may be made of multiple different technologies and have some members systems using FTN tech...
DD> Is there any restriction to using 'zone:net/1' ?
no... /1 is just another number but it has traditionally been used for *EC AKA addresses... this day in time there's not much call for *ECs but there may still be some entries in the nodelists for them...
aside from that, these are not the type of things that the FTSC is about... the way a FTN network is laid out and operated is up to that network... as long as the /0 are in place for traditional FTN host routing operations... the FTSC is about documenting and maintaining the standards used in FTNs...