This attribute gives the index of the " current" FITS header card within a FitsChan, the first card having an index of 1. The choice of current card affects the behaviour of routines that access the contents of the FitsChan, such as AST_DELFITS, AST_FINDFITS and AST_PUTFITS.

A value assigned to Card will position the FitsChan at any desired point, so that a particular card within it can be accessed. Alternatively, the value of Card may be enquired in order to determine the current position of a FitsChan.

The default value of Card is 1. This means that clearing this attribute (using AST_CLEAR) effectively " rewinds" the FitsChan, so that the first card is accessed next. If Card is set to a value which exceeds the total number of cards in the FitsChan (as given by its Ncard attribute), it is regarded as pointing at the " end-of-file" . In this case, the value returned in response to an enquiry is always one more than the number of cards in the FitsChan.

FitsChan