Procedure Vinit(var stat: VI_status_type);
   EXTERNAL;
{*USER*
 
VINIT is used to intialize the VIEWPORT interface.  The VIEWPORT interface
uses a global data area that is reserved for its exclusive use.  This area,
which is not directly accesible by the user, remains transparent to the
user.  However, it must be intialized for use by the VIEWPORT interface.
 
VINIT must be called once before any other VIEWPORT interface (Vxxxxx) calls
are made.  The status returned in STAT must be VI_SUCCESS.  If the
status is not VI_SUCCESS, a problem (normally programmer error) has
occurred, and the intialization is not complete.
 
The VIEWPORT interface can be reinitialized by calling VRESET.  DO NOT
call VINIT again as it can be executed only once.
 
VINIT is the one of four commonly used VIEWPORT interface calls (VINIT,
VSEND, VRECV and VDISC).  It will use the other VIEWPORT interface calls
for its work, making it uneccesary for the normal user to call any other
VIEWPORT interface calls.
 
*ERROR CODES*
 
VI_SUCESS - Initialization is complete.
 
VI_NO_MEMORY - Initialization failed.  Unable to allocate
               the memory needed for the field value cache area.
 
}