Allowed value types are as follows:
CDATA
NMTOKEN
NMTOKENS
ID
IDREF
IDREFS
ENTITY
ENTITIES
enumeration - eg. (hodnota1|hodnota2|hodnota3)
(hodnota1|hodnota2|hodnota3)
enumeration of notations - eg. NOTATION (notace1|notace2|notace3)
NOTATION (notace1|notace2|notace3)