%isogrk1; — Greek Letters Character Entities
               The %isogrk1; parameter entity includes the ISO 
               character entities with the public identifier:
               
               
ISO 8879:1986//ENTITIES Greek Letters//EN
ISO and the W3C are cooperating to provide an official set of character entity references for XML. A description of this set is available at http://www.w3.org/2003/entities/iso8879doc/isogrk1.html