headers.lisin the FITS extension of the NDF called hh73.
The validation process performs the following checks on each header ‘card’:
a) the length of the header is no more than 80 characters, otherwise it is truncated;
b) the keyword only contains uppercase Latin alphabetic characters, numbers, underscore, and hyphen (the header will not be copied to the extension except when the invalid characters are lowercase letters);
c) value cards have an equals sign in column 9 and a space in column 10;
d) quotes enclose character values;
e) single quotes inside string values are doubled;
f) character values are left justified to column 11 (retaining leading blanks) and contain at least 8 characters (padding with spaces if necessary);
g) non-character values are right justified to column 30, except for non-mandatory keywords which have a double-precision value requiring more than 20 digits;
h) the comment delimiter is in column 32 or two characters following the value, whichever is greater;
i) an equals sign in column 9 of a commentary card is replaced by a space; and
j) comments begin at least two columns after the end of the comment delimiter.
The validation issues warning messages at the normal reporting level for violations a), b), c), d), and i).
The validation can only go so far. If any of your header lines are ambiguous, the resulting entry in the FITS extension may not be what you intended. Therefore, you should inspect the resulting FITS extension using the command FITSLIST before exporting the data. If there is something wrong, you may find it convenient to use command FITSEDIT to make minor corrections.