Subject: Proposed TAXISnnn convention

From: thompson at stars.gsfc.nasa.gov (Bill Thompson)
Date: 1 Oct 91 15:36:52 GMT

"Multidimensional Table" Convention

One way to look at binary tables is as way of expressing data structures.  In
this view, each row is an element in a array whose data type is a structure,
and each column represents a member of this structure.

The basic binary tables convention expresses this structure array as one
dimensional.  However, one could also organize these structure elements as a
multidimensional array.  For instance, if a binary table had 15 rows, then one
could also organize this as a 5 x 3 array.

The "Multidimensional table" convention would express this organization using
the optional keywords TAXIS, TAXIS1, TAXIS2, etc., which are defined in the
manner of NAXIS, NAXIS1, NAXIS2, etc.  The product of the values of the keyword
variables TAXIS1 x TAXIS2 x ... x TAXISn is required to be equal to the total
number of rows in the binary as given by NAXIS2.  The example discussed above
would have the following values for these keywords.

        NAXIS2  =                   15  /  The table has 15 rows
        TAXIS   =                    2  /  These rows for a 2D array
        TAXIS1  =                    5  /  The first dimension is 5
        TAXIS2  =                    3  /  The second dimension is 3

The adherence to this convention will be indicated by the presence of the
keyword TAXIS, along with the associated TAXISnnn keywords.