The names of the commands working with
astrometric datatypes are usually identical to the datatypes by sake
of simplicity. The meaning of the various options
can be obtained with the command
option.
The datatype corresponding to a given kind of observations can be
learned with the command dtype.
The field structure of the records for each photometric data file can
be queried with the command field.
The names of the file associated to a given type of data can be found with
the comand nfile.