☜	USE 1977 Version of ANSI Standard					☞

3.6.16 USE

U[SE] postcond L useargument

The value of the first expr of each useargument identifies a device (or "file" or "data set"). The interpretation of the value of this expr or of any exprs in deviceparameters is left to the implementor. (See 3.6.2 for the syntax specification of deviceparameters.)

Before a device can be employed in conjunction with an input or output data transfer it must be designated, through execution of a USE command, as the "current device". Before a device can be named in an executed useargument, its ownership must have been established through execution of an OPEN command.

The specified device remains current until such time as a new USE command is executed. As a side effect of employing expr to designate a current device, $IO is given the value of expr.

Specification of device parameters, by means of the exprs in deviceparameters, is normally associated with the process of obtaining ownership; however, it is possible, by execution of a USE command, to change the parameters of a device previously obtained.

Distinct values for $X and $Y are retained for each device.

The special variables $X and $Y reflect those values for the current device. When the identity of the current device is changed as a result of the execution of a USE command, the values of $X and $Y are saved, and the values associated with the new current device are then the values of $X and $Y.

See also the transition diagram for Use.

Copyright © Standard Documents; 1977-2024 MUMPS Development Committee;
Copyright © Examples: 1995-2024 Ed de Moel;
Copyright © Annotations: 2003-2008 Jacquard Systems Research
Copyright © Annotations: 2008-2024 Ed de Moel.

This page most recently updated on 08-Jan-2024, 12:14:37.

For comments, contact Ed de Moel (demoel@jacquardsystems.com)