Each column must be of the same predefined format, and each row must contain the same number of columns. String of up to 19 characters, case insensitive.
Similar names differing only in the use of upper or lower case are indistinguishable.
Note that this is related to but distinct from the internal data type. That is, a double-precision column may be printed with limited precision although any computations using that column would be carried out in full precision. May be used by some tasks, for example, to distinguish between right ascension in hours or degrees. The default is null.