<!--===============================================-->
<!--  tm.dtd                                       -->
<!--  The interpreter of the Turing machine        -->
<!--===============================================-->

<!ELEMENT TM (Instruction, State, TapeLeft, Symbol, TapeRight)>
<!ELEMENT TapeLeft  (Node) >
<!ELEMENT TapeRight (Node) >
<!ELEMENT Node ((Square, Node) | (Square, End)) >
<!ELEMENT Symbol    (#PCDATA) >
<!ELEMENT Square    (#PCDATA) >
<!ELEMENT State (#PCDATA) >
<!ELEMENT Instruction (Instruction?) >
<!ATTLIST Instruction
                       CurrentState  CDATA #REQUIRED
                       CurrentSymbol CDATA #REQUIRED 
                       NextSymbol    CDATA #REQUIRED
                       NextState     CDATA #REQUIRED
                       Move          CDATA #REQUIRED >