The OPEN command creates a connection between a GT.M process and a device.
The format of the OPEN command is:
O[PEN][:tvexpr] expr[:[(keyword[=expr][:...])]
[:numexpr]][,...]
The optional truth-valued expression immediately following the command is a command postconditional that controls whether or not GT.M executes the command.
The required expression specifies the device to OPEN.
The optional keywords specify deviceparameters that control device behavior; some deviceparameters take arguments delimited by an equal sign (=); if the argument only contains one deviceparameter, the surrounding parentheses are optional.
The optional numeric expression specifies a time in seconds after which the command should timeout if unsuccessful; choosing 0 results in a single attempt to open the device.
When an OPEN command specifying a timeout contains no deviceparameters, double colons (::) separate the timeout numeric expression from the device expression.
An indirection operator and an expression atom evaluating to a list of one or more OPEN arguments form a legal argument for an OPEN.
For more information on OPEN, devices and deviceparameters, refer to the "Input/Output Processing" chapter in this manual.