JWST ETC Readout Patterns
The available list of readout patterns for a given instrument mode are available in the ETC in a drop-down menu on the Detector Setup tab. Only the readout patterns allowed for science are provided as options. Invalid combinations of Readout pattern and Subarray produce a warning on the Detector Setup tab and are disallowed.
The ETC does not support single group (Ngroups = 1) readout modes.
Instrument readout patterns
See also: Understanding Exposure Times