The indirect character tells the program to start reading its input
from the file specified on the remainder of the line. The
line is NOT parsed out and all characters are considered
significant for the file name. In particular, a comment field is NOT
allowed. Indirect files can be nested generally to a depth of 10,
although circumstances may reduce the acceptable depth. The default extension for
an indirect file is .XCO, although this default is under the control
of the program (in XSPEC it is .XCM and in PLT .PCO).
An example:
@filewill cause subsequent input to be read from FILE.XCO. This command file can contain strings of the form %N%, where N is an integer, which will be replaced by the Nth argument in the invocation, e.g., @file 5.0 -2 will replace %1% by 5.0 and %2% by -2. If arguments are not given on the command line, then %N% will be replaced with nothing (i.e., removed).