8.1.1 Mandatory Keywords

  The header of an ASCII table extension must use the keywords defined in Table 8.1. The  first keyword must be XTENSION; the seven keywords following XTENSION (BITPIX ... TFIELDS) must be in the order  specified with no intervening keywords.

 

1 XTENSION

2 BITPIX

3 NAXIS

4 NAXIS1

5 NAXIS2

6 PCOUNT

7 GCOUNT

8 TFIELDS ... (other keywords, which must include ...) TBCOLn, n=1, 2, ..., k where k is the value of TFIELDS TFORMn, n=1, 2, ..., k where k is the value of TFIELDS ...

last END

XTENSION Keyword

The  value field shall contain the character  string value text 'TABLE'.

BITPIX Keyword

The value field shall contain the integer 8, denoting  that the array contains ASCII  characters.

NAXIS Keyword

The value field shall contain the integer 2, denoting  that the included data array is two-dimensional: rows and columns.

NAXIS1 Keyword

The value field shall contain a non-negative integer, giving  the number of ASCII characters in each row of the table.

NAXIS2 Keyword

The value field shall contain a non-negative integer, giving  the number of rows in the table.

PCOUNT Keyword

The value field shall contain the integer 0. 

GCOUNT Keyword

The value field shall contain the integer 1; the data  records contain a single table.

TFIELDS Keyword

The value field shall contain a non-negative integer representing  the number of fields in each row. The maximum permissible value is 999.

TBCOLn Keywords

The value field of this indexed keyword shall contain an integer  specifying the column in which field n starts. The first column of a row is numbered 1.

TFORMn Keywords

The value field of this indexed keyword  shall contain a character string describing the format in which field n is encoded. Only the formats  in Table 8.2, interpreted as ANSI FORTRAN-77 [13] input  formats and discussed in more detail in §8.1.5, are permitted for encoding. Format codes must be specified in upper case. Other format editing codes common to ANSI FORTRAN-77 such as repetition, positional editing, scaling, and field termination are not permitted. All values in numeric fields have a number base of ten (i.e., they are decimal); binary, octal, hexadecimal, and other representations are not permitted.

 

Field Value Data Type

Aw Character

Iw Decimal integer

Fw.d Single precision real

Ew.d Single precision real, exponential notation

Dw.d Double precision real, exponential notation

END Keyword

This keyword has no associated value. Columns 9-80  shall contain ASCII blanks.