! U2205 is the empty set
keycode 19 = 0 parenright emptyset
! U207B is superscript minus
+! U2212 is MINUS SIGN
! U2213 is minus-or-plus
-keycode 20 = minus underscore notsign U2213
+keycode 20 = minus underscore U2212 U2213
keycode 21 = equal plus notequal plusminus
! U221A is the square root sign (radical)
! U211A is the set of all rationals