anchor.diff:  (defclass  sf-double (x3d-field)
     ()
     (:documentation "
  -ISO/IEC 19775-1:2008
  +ISO/IEC 19775-1:2008 (SEE NOTICE.TXT)
   
   5.3.4 SFDouble and MFDouble
   
  
positive.code: (defclass  mf-color (x3d-array-field)
    ()
    (:documentation "
  ISO/IEC 19775-1:2008
  
  5.3.2 SFColor and MFColor
  
  
negative.code: (defclass  sf-vec4f (x3d-field)
    ()
    (:documentation "
  ISO/IEC 19775-1:2008 (SEE NOTICE.TXT)
  
  5.3.21 SFVec4f and MFVec4f
  
  