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Subsections
The SIMPLE keyword is
required to be the first keyword in the primary
header of all FITS files, including those with random
groups records. If the random groups format
records follow the primary header, the card
images of the primary header must use the keywords
defined in Table 7.1 in the
order
specified. No other keywords may intervene between
the SIMPLE keyword and the last NAXISn keyword.
Table 7.1:
Mandatory keywords in primary header preceding random groups.
| 1 |
SIMPLE |
| 2 |
BITPIX |
| 3 |
NAXIS |
| 4 |
NAXIS1 |
| 5 |
NAXISn, n=2, ..., value of NAXIS |
| |
|
| |
(other keywords, which must include ...) |
| |
GROUPS |
| |
PCOUNT |
| |
GCOUNT |
| |
|
| last |
END |
The total number of bits in the random groups records
exclusive of the fill described in §7.2 is
given by the following
expression:
| Nbits = |BITPIX| × GCOUNT × (PCOUNT + NAXIS2 × NAXIS3 × ... × NAXISm), | (7.1) |
where Nbits is
non-negative and the number of bits excluding fill,
m is the value of NAXIS, and
BITPIX, GCOUNT,
PCOUNT, and the NAXISn
represent
the values associated with those keywords.
The card image containing this keyword is structured in
the same way as if a
primary data array
were present (§5.4.1).
The card image containing this keyword is structured as
prescribed in
§5.4.1.
The value field shall contain an integer ranging from 1 to
999, representing one more than the number of axes in each
data array.
The value field shall contain the integer 0, a signature of
random groups format indicating that there is
no primary data array.
The value field shall contain an integer, representing
the number of positions along axis n-1 of the
data array in each group.
The value field shall contain the logical constant T.
The
value T associated with this keyword implies that random groups
records are present.
The value field shall contain an integer equal to the
number
of parameters preceding each array in a group.
The value field shall contain an integer equal to the
number of random groups present.
The card image containing this keyword is structured as described
in §5.4.1.
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5/13/1999