Examples

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

    b1,b2,b3,b4
  

  
  This means ``Use b1.sdf, b2.sdf, b3.sdf and b4.sdf''. It is assumed that the NDFs are the top level objects within the .sdf files.

    cena_b1-
  

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

    *
  

  
  This means ``Use all .sdf 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 NDFs from the text file files.lis.

    ../data/*
  

  
  This means ``Use all .sdf files contained in the UNIX directory ../data''.
• If an application asks for a group of output NDFs, 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 NDFs from text file out.dat''.

    *_ds
  

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

    ../bk/*|_ds|_bk|
  

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

Group expressions can be used to specify objects other than NDFs. 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:

  10,11,21,-10,0,0

This gives the indices as a comma separated list.

  10,11-
  21,-10-
  0,0

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

  ^pixels.dat

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

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