GOST R ISO 10303-21-1999 Industrial automation systems and integration. Product data representation and exchange. Part 21. Implementation methods. Clear text encoding of exchange structure
2002GOST R ISO 10303-21-2002 Industrial automation systems and integration. Product data representation and exchange. Part 21. Implementation methods. Clear text encoding of the exchange structure
1999GOST R ISO 10303-21-1999 Industrial automation systems and integration. Product data representation and exchange. Part 21. Implementation methods. Clear text encoding of exchange structure