### 7 Altering program parameters

When a PHOTOM application is started, the initial selection of most of the parameters is taken from the previous run of the routine. The parameter values are stored in the GLOBAL.sdf or application_name.sdf files in the $\sim$/adam directory at the end of a run. The current values can be examined using the HDSTRACE facility (SUN/102). To clear these values, and to revert to the start-up defaults the GLOBAL.sdf and application_name.sdf files have to be deleted.

The starting values of the parameters can also be specified within the ADAM command language. The keyword facility allows the parameters to be given on the command line (see SG/4, the ADAM User’s Manual). The keywords have the same name as the parameters; for example the search box for the centroiding can be changed using the command.

ICL> photom search=5

From the C-shell the keywords can be included on the command line.

% photom search=5