Data Object: Every VHDL code needs some identifiers as the name of either the keyword or user-defined name as stated above. Those identifiers or elements which are used to hold some values are viewed in VHDL as a so called object or data object.  Each data object of a VHDL program must be declared prior to its use. A data object holds a value of some specified type. The declaration syntax of a data object  is : OBJECT_CLASS        identifier [,identifier ...] :        TYPE [:=value]; In the above syntax, an identifier is the name specified to the object, and type is the permitted kind of value that a object can have. Object class specifies the class of the object which may be classified