#define NGROUPS 10 /* number of mpx files permitted at one time */
#define NCHANS 20 /* number of channel structures */
#define NPORTS 30 /* number of channels to i/o ports */
#define NMSIZE 50 /* max size of mxlstn file name */
* header returned on read of mpx
* head expected on write of mpx
* internal structure for channel
* control channel message codes
* debug codes other than mpxchan cmds
#define MXLSTN (('x'<<8)|1)
#define MXNBLK (('x'<<8)|2)