<\body> Brackets inside mathematical formulas should always match: as soon as you enter an opening bracket ``('', will automatically insert the matching closing bracket ``)''. You may disable this feature using . Attention (see also below): brackets in old documents will be automatically upgraded to matching brackets. Sometimes, you do not want the closing bracket, or you may want to replace it by another closing bracket. No problem: if your cursor is just before the closing bracket inside |)>>, then pressing will turn the expression into >. Alternatively, deletion of a bracket will actually turn it into an , after which you can replace it by an arbitrary opening or closing bracket. By default, the sizes of the brackets are adjusted to the expression between the brackets. Small delimiters, which are created using the -prefix, keep their sizes independently of the enclosed expression. Alternatively, you may use in order to toggle between large and small delimiters. For some delimiters, such as , the opening and closing delimiters coincide. For instance, entering a vertical bar will produce an absolute value. The (small) bar-separator is obtained using , or as a variant using . The big bar-separator is entered using . In and , such large separators do not exist; they are used for producing the vertical bars in formulas like <\equation*> ||\>. There may be as many middle delimiters between a left and a right delimiter as one wishes. Notice that there are still another number of variants of vertical bars. For instance, the binary relation ``divides'' is entered using > or . In , large delimiters may either be ``left delimiters'', ``right delimiters'' or ``middle delimiters''. By default, and > are left delimiters, and > are right delimiters. But there status can be changed using the , and key combinations. For instance, produces , considered as a large left delimiter. Sometimes you may want large delimiters of a particular size, instead of self-adjusting ones. This can be achieved by resizing the expression in between the brackets using the items in . Notice that it is possible to insert a pair of invisible brackets using . This is for instance useful in computational contexts, in which formulas should admit a precise, not merely visual semantics. Alternatively, one may put the formula inside a ``rigid box'' using, which additionally prevents the formula from being hyphenated. <\initial> <\collection>