The detection of any response prefixed by ``@" is taken as being a reference to an Indirect Command File, from which further Input will be taken until the end of file is detected, at which point input will be redirected to the keyboard. Note that this response may be made at any time, even when being prompted to supply an Integer value for example. Command Files have the default file extension .UIC and thus the response:-
@Filename
is taken as referring to Filename.UIC, while the response
@
is taken as referring to UIPACK.UIC by default. Indirect Command Files may
themselves reference other Command Files, where such references may be nested
up to a maximum of 4 deep.
If UIPACK cannot open the requested Command File (because of a bad filename
syntax or non-existent file), an error message will be issued and the request
will be ignored. If the error occurs within a nested Command File, the Command
File Stack will be unwound and further input will be redirected to the keyboard.
A Subprogram is available as an alternative to requiring the User to
indicate that a Command File should be used for further input. This could be
used to setup the internal configuration for an Application Program for
example.