Input FITS file, or stack of files (see "ahelp stack" for more information), with an optional FITS extension in brackets, e.g. "filename.fits[GTI2]". By default, the tool reads the header from the principal block (e.g. EVENTS, EVENTS_IMAGE), not the primary block.

Name of the text file receiving parameter values, which must end in '.par'. When using a stack of input files, there must be an equal number of output filenames given.

The template file is formatted as a CIAO parameter file and must end in '.par'. A stack of files may be used. If "NONE", all header keywords will be written to the output file. If a template file is given, only keywords which appear both in the file header and the template file will be written to the output file. If an empty or missing template file is specified, the tool will exit with an error and create an empty output file.

A short template file might look like:

CONTENT,s,h,"EVT1",,,"NEWNAME"
TELESCOP,s,h,"CHANDRA",,,""
INSTRUME,s,h,"ACIS",,,""
DETNAM,s,h,"ACIS-7",,,""
GRATING,s,h,"NONE",,,""
OBJECT,s,h,"0235+164",,,""

The first three fields are required, but only the first and last fields are used. The first field contains the keyword name and the last field contains an optional new name for the keyword in the output file. If the last field is "", the name of the keyword is the same in the output file as in the input file.

Possibilities are "same", "upper", and "lower". If "same", the case of keywords in the input file will be preserved in output file. Otherwise, the case is forced to upper or lower.

Reports the input and output filenames, as well as any warnings.

Specifies whether or not to overwrite an existing output file. If "no" and the output file exists, the tool exits with an error.