<\body> Starting with version 1.0.7.10, incorporates several features for the ``semantic'' editing of mathematical formulas. When used appropriately, this allows you to write documents in which all formulas are at least correct from a syntactical point of view. For instance, in the formulas , the computer will understand that is an operator which applies to the arguments and . Notice that our ``semantics'' does not go any further: is unaware of the mathematical nature of addition. Semantic editing does require additional efforts from the user, at least a little adaptation. For instance, it is the user's job to enter multiplications using the shortcut and function applications using . Indeed, from the graphical point of view, these operations cannot be distinguished, since they are both printed as invisible whitespace. However, the semantics of these operations is clearly very different. Although semantically correct documents are usually not very different from informal presentation-oriented documents as far as typesetting is concerned, the additional user effort may pay off for several reasons: <\itemize> Documents with more semantics are for instance useful when using formulas as inputs for a computer algebra system. Syntactically correct documents are less likely to contain ``typos'' or more intricate mathematical errors. For certain editing operations, such as cut and paste, one may directly select subformulas which are meaningful from the syntactical point of view. It reduces the risk of using non standard notations, which will be difficult to understand for potential readers of your work. Furthermore, other semantic facilities might be integrated in the future, such as semantic search and replace, or semantic search on the web. In order to activate the semantic editing facilities, please toggle . In the semantic editing mode, several of the structured editing features of apply to the syntactic structure of the formula, rather than the visual structure of the document. For instance, the is usually a subformula of the . Similarly, only syntactically meaningful subformulas can be selected when making a selection. The semantic focus is useful for several reasons. First of all, it is displayed in green if the formula is syntactically correct and in red if you made an error. This allows to quickly notice any typos while entering a formula. Secondly, if you have any doubt on the precedence of a mathematical operator or relation, then the semantic focus will inform you on the default interpretation: by putting your cursor right next to your operator, the subexpression to which the operator applies will be highlighted. In the case of an addition, or a more general associative operator, all summands are highlighted. <\initial> <\collection>