### AST_SETFITSU

Store an undefined keyword value in a FitsChan

#### Description:

This routine stores an undefined value for a named keyword within a FitsChan at the current card position. The new undefined value can either over-write an existing keyword value, or can be inserted as a new header card into the FitsChan.

#### Invocation

CALL AST_SETFITSU( THIS, NAME, COMMENT, OVERWRITE, STATUS )

#### Arguments

##### THIS = INTEGER (Given)
Pointer to the FitsChan.
##### NAME = CHARACTER $\ast$ ( $\ast$ ) (Given)
A character string containing the FITS keyword name. This may be a complete FITS header card, in which case the keyword to use is extracted from it. No more than 80 characters are read from this string.
##### COMMENT = CHARACTER $\ast$ ( $\ast$ ) (Given)
A string holding a comment to associated with the keyword. If a blank string is supplied, then any comment included in the string supplied for the NAME parameter is used instead. If NAME contains no comment, then any existing comment in the card being over-written is retained. Otherwise, no comment is stored with the card.
##### OVERWRITE = LOGICAL (Given)
If .TRUE., the new card formed from the supplied keyword name and comment string over-writes the current card, and the current card is incremented to refer to the next card (see the "Card" attribute). If .FALSE., the new card is inserted in front of the current card and the current card is left unchanged. In either case, if the current card on entry points to the " end-of-file" , the new card is appended to the end of the list.
##### STATUS = INTEGER (Given and Returned)
The global status.

#### Notes:

• If, on exit, there are no cards following the card written by this function, then the current card is left pointing at the " end-of-file" .

• An error will be reported if the keyword name does not conform to FITS requirements.