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There are a few limitation built into the FITSIO interface that users
should be aware of:
- *
- The maximum number of FITS files that may be simultaneously opened
by a single program is defined by the 'nb' parameter and is currently
set to 12, except in the IBM PC versions where the maximum is only 3
files to reduce memory requirements. To increase this limit, one must
globally increase the value of this parameter throughout the FITSIO code.
One must also add a corresponding common block buffer (e.g., common
blocks ft00b1, ft00b2, ft00b3, ... ft0b12) in the following
subroutines: ftgbyx, ftgcbf, ftpbyx, ftpcbf, and ftzero. The nested
set of IF...ELSE IF statements in each of these subroutine must then
be extended to deal with the additional file buffers.
- *
- The maximum number of extensions allowed in a FITS file is 128 as defined
by the 'ne' parameter in the code.
- *
- The maximum number of columns allowed in an ASCII or binary table is
defined by the parameter called 'nf' used throughout the code and is
currently set to 512. By definition, a FITS table may not have more than
999 columns because the TFORMnnn and TTYPEnnn keywords allow only a 3
digit sequence number. There is no limit to the number of rows allowed
in a table. Similarly, there is no intrinsic limit to the size of the
primary array or to the number of groups in a 'random grouped' FITS file.
- *
- The maximum size of a FITS file supported by FITSIO is 2**31 bytes,
which is approximately 2.14 GBytes. This limit is imposed by the use
of Integer*4 variables as pointers to byte locations within the FITS file.