A reference page for items commonly found in MSes but not described by the MS definition
Obviously everything here is optional. However, some things are expected in certain situations, and often the presence of one requires other optional columns to be present. Many of these are lumped under the term "scratch columns".
MODEL_DATA + CORRECTED_DATA
Complex data type, same shape as DATA (or LAG_DATA?)
(Float) This seems to have a unique shape - it's a Vector with length equal to the number of channels (or lags?). I'm not sure why IMAGING_WEIGHT is allowed to vary with channel but not polarization.
for why, if you approach things correctly, you can ignore whether or not SORTED_TABLE is present.
NS_WX_STATION_ID + NS_WX_STATION_POS
These appear in MSes from the EVLA. (Currently split drops them, though.) Does anyone have more info on them?