The following sequence of routine calls illustrate a simple example of reading an existing FITS file.
1. Open the file with fits_open_file / ffopen. 2. Read any desired header keywords with fits_read_key / ffgky. 3. Read the primary data, if any, with fits_read_img / ffgpv. 4. Repeat steps 2 and 3 until all the desired information has been read. 5. Move to another extension with fits_movabs_hdu / ffmahd. 6. Read any extension header keywords with fits_read_key / ffgky. 7. Read any table column of data with fits_read_col / ffgcv. 8. Repeat steps 6 and 7 until all the information has been read. 9. Repeat steps 5 through 8 for any other extensions. 10. Close the file with fits_close_file / ffclos.