as category header index matches read_name read_version readCategory readName readVersion size_in_file type update_checksums update_name update_version updateChecksums updateName updateVersion verify_checksums verifyChecksums

size_in_file() std::size_t size_in_file ( ) const Read the number of bytes used by the Hdu. Total number of bits in the extension data array exclusive of fill that is needed after the data to complete the last record. According to doc: https://archive.stsci.edu/fits/fits_standard/node39.html#s:conf