### CCDNDFAC

Accesses a list of images and writes their names to a file

#### Description:

This routine accesses a list of images and writes their names to a text file. It is intended to be used as an aid to producing procedures which require the facilities of image list access used in CCDPACK. For this reason the usual application introductory message is suppressed. The names of the images may be written out to the terminal as an aid to memory. If no images are accessed then the output file will not be created, testing for the existence of this file is a platform independent way of determining if the invocation has been successful.

#### Usage:

ccdndfac namelist echo

#### Parameters:

If TRUE then the names of the images will be written to the terminal unless there is only one input image. [TRUE]
Name of the CCDPACK logfile. If a null (!) value is given for this parameter then no logfile will be written, regardless of the value of the LOGTO parameter.

If the logging system has been initialised using CCDSETUP then the value specified there will be used. Otherwise, the default is "CCDPACK.LOG". [CCDPACK.LOG]

Every CCDPACK application has the ability to log its output for future reference as well as for display on the terminal. This parameter controls this process, and may be set to any unique abbreviation of the following:
• TERMINAL – Send output to the terminal only

• LOGFILE – Send output to the logfile only (see the LOGFILE parameter)

• BOTH – Send output to both the terminal and the logfile

• NEITHER – Produce no output at all

If the logging system has been initialised using CCDSETUP then the value specified there will be used. Otherwise, the default is "BOTH". [BOTH]

A list of image names. The image names should be separated by commas and may include wildcards. [!]
The maximum number of images which should be accessed. If a null return "!" is given for this parameter then the normal CCDPACK limit will be applied. [!]
The name of the output file to contain the names of the accessed images. [CCDNDFAC.LIS]

#### Examples:

ccdndfac image_name_list true
In this example the list of image names is written to image_name_list and the image names are echoed to the terminal. No constraint is placed on the number of images accessed (other than the normal CCDPACK limit).
ccdndfac image_name true maxndf=1
In this example only a single image name is accessed. The name is not echoed to the terminal (even though echo is set TRUE).

#### Behaviour of parameters

All parameters retain their current value as default. The "current" value is the value assigned on the last run of the application. If the application has not been run then the "intrinsic" defaults, as shown in the parameter help, apply.

Retaining parameter values has the advantage of allowing you to define the default behaviour of the application. The intrinsic default behaviour of the application may be restored by using the RESET keyword on the command line (you may well want to do this when using the application from a procedure).

Certain parameters (LOGTO and LOGFILE) have global values. These global values will always take precedence, except when an assignment is made on the command line. Global values may be set and reset using the CCDSETUP and CCDCLEAR commands.