Loading and Running Tasks
From CASA Guides
There are three distinct ways to invoke a task in CASA. The first:
default('clean')
will load up a task with the default parameters.
The second---equivalent to TASK in AIPS---will invoke a task, but will transfer over any currently-used parameters to that "new" task (the rest it will set to defaults).
inp clean
This might come in handy if, say, you have already set the 'vis' and 'spw' parameters for one task, and would like to use these same settings in another task.
Finally, the third option is:
tget clean
which is conveniently equivalent to TGET in AIPS This will recall the parameters from the last time the invoked task was run successfully.