Sets the “INCLUDE” or “IGNORE” marked section switch for the MATHML 2.0 Tag Set or MathML 3.0 Tag Set. This switch determines whether the math processing in the appropriate MathML Tag Set (%mathml2.dtd; or %mathml3.dtd;) module or the %xmlspecchars.ent; module will invoke the sets of special characters that are defined AND INVOKED in the %xmlspecchars.ent; module. A value of “IGNORE” turns off the second invocation, which is located in the MathML Tag Set.