Examples

• If an application asks for a group of input data files, the following are all possible responses:

    b1,b2,b3,b4
  

  
  

  This means ``Use the NDFs stored in files b1.sdf, b2.sdf, b3.sdf and b4.sdf''. If automatic format conversion is being used (see here), then an example such as:

    b1.fit,b2.fit,b3.fit,b4.fit
  

  is also legal, and reads the corresponding FITS files.

    cena_b1-
  

  
  

  This means ``Use cena_b1.sdf and then (because of the minus sign at the end) ask the user for more data files''.

    *
  

  
  This means ``Use all accessible data files in the current directory''.

    hh1_b1s*_ds
  

  
  This means ``Use hh1_b1s1_ds.sdf, hh1_b1s2_ds.sdf, etc''.

    ^files.lis
  

  
  This means ``Read the names of data files from the text file files.lis.''

    ../data/*
  

  
  This means ``Use all accessible data files contained in the directory ../data''.

• If an application asks for a group of output data files, the following are possible responses:

    file1,file2,file3
  

  
  This means ``Create file1.sdf, file2.sdf and file3.sdf''.

    ^out.dat
  

  
  This means ``Read the names of the output data files from text file out.dat''.

    *_ds
  

  
  This means ``Append the string ``_ds'' to the end of all the input data file names.

    ../bk/*|_ds|_bk|
  

  
  This means ``Substitute the string ``_bk'' for all occurrences of the string ``_ds'' in the input data file names, and put the files in directory ../bk''.

Group expressions can be used to specify objects other than data files. For instance, if an application asks for a group of pixels to be specified by their X and Y pixel indices, then the pixels (10,11), (21,-10) and (0,0) could be specified in any of the following ways:

1.   10,11,21,-10,0,0
   

   
   
   This gives the indices as a comma separated list.
   
   

2.   10,11-
     21,-10-
     0,0
   

   
   
   Ending each line with a minus sign causes the user to be re-prompted for more values.
   
   

3.   ^pixels.dat
   

   
   
   The file pixels.dat is read. The file could contain the following four lines:

4.   #  Approximate star centres.
     10,11
     21,-10
     0,0