Software Rules

• The calling hierarchy: GE $\Rightarrow$ GED $\Rightarrow$ (GEDA) $\Rightarrow$ GEDX $\Rightarrow$ GEP $\Rightarrow$ GEB is strict; each level can only call levels below it. So at any one time there can only be at most one of each of the above types active. This allows each level to be allocated a set of temporary reference links to be used to access the the titles.

• The geometry uses three coordinate systems each associated with a software tier:-
  • Detector coordinates are used by the interface. These are Cartesian with the origin at the centre of the acrylic vessel.

  • Detector element coordinates are used in the detector element routines and are Cartesian with the origin at the centre of the GED under consideration.

  • Primitive coordinates are used in the GEP routines. They are again Cartesian with the origin at the centre of the primitive.

• If an error is detected in any routine it should be reported to ge_tell as follows:-

  calling sequence:-

  call ge_tell( routine_name, err_mess, id_err )
  

  parameters (all input only)

  
  routine_name 		  char string: name of calling routine
  
  
  e.g. 'GE_NEXT'.
  
  
  err_mess 		  char string: error text e.g. 'Bad XYZ'.
  
  
  id_err 		 error number. Must be defined in id_errors.inc.
  

  ge_tell will call ztell and won't return to caller.

The remaining rules concern specific layers.