A group expression is obtained from the environment using the supplied parameter. The expression is parsed (using the facilities of the GRP routine GRP_GROUP,see SUN/150) to produce a list of explicit names for existing catalogues which are appended to the end of the supplied group (a new group is created if none is supplied). If an error occurs while parsing the group expression, the user is re-prompted for a new group expression. CAT identifiers for particular members of the group can be obtained using CTG_CATAS.

CALL CTG_ASSOC( PARAM, VERB, IGRP, SIZE, FLAG, STATUS )

PARAM = CHARACTER$\ast$($\ast$) (Given)

VERB = LOGICAL (Given)

IGRP = INTEGER (Given and Returned)

SIZE = INTEGER (Returned)

FLAG = LOGICAL (Returned)

STATUS = INTEGER (Given and Returned)

• Any file names containing wildcards are expanded into a list of catalogue names. The supplied strings are intepreted by a shell (/bin/tcsh if it exists, otherwise /bin/csh, otherwise /bin/sh), and so may contain shell meta-characters (e.g. twiddle, $HOME, even command substitution and pipes - but pipe characters "$|$" need to be escaped using a backslash "$\setminus$" to avoid them being interpreted as GRP editing characters).

• Only the highest priority file with any give file name is included in the returned group. The priority of a file is determined by its file type. Priority decreases along the following list of file types: .FIT, .fit, .FITS, .fits, .GSC, .gsc, .TXT, .txt, .Txt, .sdf. If no file type is given by the user, the highest priority available file type is used. If an explicit file type is given, then that file type is used.

• Names of catalogues stored in FITS format may include an FITS extension number. For instance, "/home/dsb/mydata.fit{3}" refers to a catalogue stored in the third extension of the FITS file mydata.fit.

• Catalogues stored in HDS format must be stored as the top level object within the .sdf file.

• All matching files are opened in order to ensure that they are valid catalogues. The user is notified if there are no valid catalogues matching a supplied name, and they are asked to supply a replacement parameter value.

• Each element in the returned group contains a full specification for a catalogue. Several other groups are created by this routine, and are associated with the returned group by means of a GRP owner-slave relationship. These supplemental groups are automatically deleted when the returned group is deleted using GRP_DELET. The returned group should not be altered using GRP directly because corresponding changes may need to be made to the supplemental groups. Routines CTG_SETSZ, CTG_GTSUP and CTG_PTSUP are provided to manipulate the entire chain of groups. The full chain (starting from the head) is as follows:

  • FITS extension numbers (if any)

  • File types

  • Base file names

  • Directory paths

  • Full catalogue specification (this is the returned group IGRP)

• If an error is reported the group is returned unaltered. If no group is supplied, an empty group is returned.

• A null value (!) can be given for the parameter to indicate that no more catalogues are to be specified. The corresponding error is annulled before returning unless no catalogues have been added to the group.

• If the last character in the supplied group expression is a colon (:), a list of the catalogues represented by the group expression (minus the colon) is displayed, but none are actually added to the group. The user is then re-prompted for a new group expression.