Columns must be declared using the astAddColumn method before values can be stored within them. This also fixes the type and shape of the values that may be stored in any cell of the column. Cells may contain scalar or vector values of any data type supported by the KeyMap class. Multi-dimensional arrays may also be stored, but these must be vectorised when storing and retrieving them within a table cell. All cells within a single column must have the same type and shape, as specified when the column is added to the Table.
Tables may have parameters that describe global properties of the entire table. These are stored as entries in the parent KeyMap and can be access using the get and set method of the KeyMap class. However, parameters must be declared using the astAddParameter method before being accessed.
Note - since accessing entries within a KeyMap is a relatively slow process, it is not recommended to use the Table class to store very large tables.
AST A Library for Handling World Coordinate Systems in Astronomy