<\body> We have done our best to support most of the classical mathematical notations. Nevertheless, the user may sometimes want to define notations with a non standard semantics. Certain areas may also require special notations which are not supported by default. provides a very simple primitive, which allows the user to manually override the default syntactical semantics of a formula. Assuming that semantic editing was activated, you may insert the primitive using or . The first argument contains the formula as it should be displayed, whereas the second argument contains the formula as it should be interpreted. For instance, if we enter > as the first argument and > as the second one, then the > will be interpreted as a binary relation, exactly in the same way as >. Moreover, the spacing around > will be adapted, so as to mimick the spacing around >. In this particular example, we might have obtained the same result by using the primitive, which is equivalent to with> as its second argument. Most standard operator types are available from , or using the keyboard prefix. In particular, you may use to simply ignore a formula and in order to make the formula behave as an ordinary symbol (such as the letter ``o''). The primitive is especially powerful when used in combination with the macro language. For instance, consider the formula *\*|f*\ z>>. It is likely that the inteded interpretation of *\> is *\|)>> and not *\*\>. Therefore, if we often use the constant *\>, then we might want to define a macro by <\tm-fragment> *\>|*\)>>>>>>> Such macros may be grouped together into a style package with the user's favourite notations. Future versions of might also provide style packages with notations dedicated to specificareas. Let us finally notice that there are usually several ways for redefining the semantics of a formula. For instance, an alternative way to define the macro is using <\tm-fragment> |2*\*\|\>>>>>> where we inserted a pair of invisible brackets around *\>. Similarly, in the formula <\equation*> \+\+\+\>+log log log x>+log log x>+log x>, we may either select the whole formula and give it the semantics of an ordinary symbol, by pressing. However, a nicer solution is to only select the subformula \>>, and give it the semantics of an ordinary symbol. Yet another example is the sign sequence mentioned earlier. This sequence can be interpreted correctly by inserting invisible separators between the different signs using the shortcut. <\initial> <\collection>