Three aspects of TLI are left
to be defined by a particular transport provider:
pathnames to open with the t_open function,
and the types of service provided with them
the syntax and semantics of transport addresses, used
with the t_accept, t_bind,
t_connect, t_listen,
t_rcvconnect, t_rcvudata,
t_rcvuderr, t_snddis,
and t_sndudata functions
the syntax and semantics of transport provider options,
specified in the arguments to the t_accept,
t_optmgmt, t_rcvconnect, t_rcvudata,
t_rcvuderr, t_snddis,
and t_sndudata functions