AIPS makes the distiction between tasks, verbs,
procedures, pseudo verbs and adverbs. A task is a process
that is shed by the AIPS program and runs in the background so that
control of the AIPS program is returned straight away to the user.
They are generally used for long comptational jobs. Verbs are processes
that are actually run by the AIPS program itself. They do not run in
the background, and control of the AIPS program is not returned until
they are finished. They are typically used for short computational jobs
or interactive graphics processes. An example is the verb to list an
image header, IMHEAD. Procedures are essentially scripts or macros
that the user defines within AIPS. They are built from standard AIPS\
commands and are very useful for chaining together tasks and verbs.
Pseudo verbs are commands that set some characteristic that the AIPS\
program then uses in the future. An example is the command DEBUG
true which instructs AIPS that should a task be compiled and linked
with the debugger, then it should be started in debug mode. Adverbs are
the arguments to tasks, verbs and pseudo verbs which pass information
from the user to the process.
Tasks, verbs and procedures can all be activated with the GO
command such as GO ATLOD (a task), GO IMHEAD (a verb),
or GO ATCALIB (a procedure). In addition, verbs
and procedures can also be activated by commanding the verb or procedure
name only without the GO, but some people would rather not know
this. Pseudo verbs can only be activated by commanding the pseudo
verb's name followed by its argument, if any. Adverbs are passive only
and don't GO anywhere. You assign values to them with
statements such as optyp='load' (strings are quoted) or
nfiles=10.
I will probably use words such as task, verb, and command interchangeably
in this manual.