text: #ifndef cg_dfn_h
  #define cg_dfn_h
  
  /*
   * Flags which mark a symbol as topologically ``busy'' or as
   * topologically ``not_numbered'':
   */
  #define	DFN_BUSY	-1
  #define	DFN_NAN		0
  
  /*
   * Depth-first numbering of a call-graph.
   */
  
  extern void cg_dfn (Sym * root);
  
  #endif /* cg_dfn_h */
  