7.2 Data Sequence

  Random groups data shall consist of a set of groups. The number of groups shall be specified by the GCOUNT keyword in the associated header record. Each group shall consist of the number of  parameters  specified by the PCOUNT keyword  followed by an array with the number of elements N_elem given  by the following  expression:

Nelem = (NAXIS2 × NAXIS3 × ... × NAXISm),

(7.3)

where N_elem is the number of elements in the data array in a group, m is the value  of NAXIS, and  the NAXISn represent the values associated with those keywords.

The first parameter of the first group shall appear in the first location of the first data record. The first element of each array shall immediately follow the last parameter associated with that group. The first parameter of any subsequent group shall immediately follow the last element of the array of the previous group. The arrays shall be organized internally in the same way as an ordinary  primary data array. If the groups data do not fill the final record, the remainder of the record shall be filled  with zero values in the same way as a primary data array (§4.3.2). If random groups records are present, there shall be no primary data array.