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Null statement shows the no action is needed. This is mainly used in case statements. It is also used to indicate conditions and action to be executed. This keyword is used for "no operation" statements. The syntax is :

null;

Ø Example :

case OPCODE is

when "001" => TD := SRA and SRB;

when "010" => TD := SRA or SRB;

when "100" => TD := not SR;

when others => null;

end case;