Exchange/SNA Manual

OPEN Procedure
Exchange/SNA System Procedure Calls
104700 Tandem Computers Incorporated 5–13
The name you specify for the line server must be the name assigned to that line
server when it was started. Typically, you would use the NAME parameter in the
RJECIS command or the Exchange/SNA SET command to assign a name to the
line server. See the RJECIS command and the SET command in Section 3 for more
information.
If you are opening a printer, punch, or card-reader subdevice, the subdevice’s
name consists of the name of a class of subdevices and, optionally, the unit
number of an individual subdevice within the specified class of subdevices. The
unit number must immediately follow the subdevice class name with no
intervening blanks.
The subdevice class name must be one to six alphanumeric characters, of which
the first must be a letter. It must be the name of a subdevice class that was defined
when the line server was started.
The unit number must be a number between one and the maximum number of
subdevices of the specified class that are supported by the line server. If you omit
the unit number, the first available unit within the specified subdevice class is
opened.
If you are opening the console subdevice, do not specify a unit number. There is
only one console subdevice, and no unit numbers are used with the console
subdevice. The console name must be one to six alphanumeric characters, of
which the first must be a letter.
filenum
INT:ref:1
returns a number that your program uses to identify the Exchange/SNA
subdevice in subsequent file-system procedure calls. This number is assigned by
the file system and is unique among all files that your program has open at once.
If the call to OPEN fails, filenum is set to -1.
flags
INT:value
specifies certain attributes of the file and how it is opened. The individual bit
fields are described below.
.<0:3> Must be 0.
.<4:5> Specifies how your program will access the subdevice.
0 = Read/write access (allowed with only the console subdevice)
1 = Read-only access (required for printer and punch subdevices)
2 = Write-only access (required for card-reader subdevices)
3 = Reserved, causes an error if specified.
.<6:7> Must be 0.