+PortReader : ReaderWriter :: CanRead ->
 PtIn : In
 PortCtl : Ctl
 Statistics : ?
;

In PortReader = < &String, String, RW_* = RW_CMD_WAIT >
Ctl PortReader = < String, String >

!CanRead ->
 '%In', '%Ctrl'
;

Reader = PortReader [StatLog]
StatLog Reader = List : DateTime <- String