<\body> In this section, we describe how fills pages with typesetted content. Besides specifying the settings on how to print a document, the user may also determine the way pages should be rendered on screen. It should be noticed that the number of environment variables is redundant in the sense that some variables are computed as a function of other ones. For instance, by default, the paragraph width is computed as a function of the page size and the left and right margins. <\explain> <|explain> Specify the size of a page when printing out. Most standard formats are available in . By default, the paper size is the one of your printer (the default printer settings may be changed in ). When the is set to , then the page size is given by and . <\explain> <|explain> The orientation of pages can be either or . <\explain> <|explain> The current page number. This environment variable should be manipulated with care, since it is not yet available at typesetting time. For a reliable determination of page numbers, one may combine the and primitives. Nevertheless, the variable can be used in the macros which render page headers and footers. <\explain> <|explain> This environment variable really contains the macro which is used for rendering the page-number. By default, it renders . The macro takes no arguments. In order to simulate a document whose first page number is , one may redefine <\tm-fragment> |122>>>> <\explain> <|explain> This parameter specifies the page breaking algorithm. The default algorithm takes into account the global document and tries hard to avoid bad page breaks. The alternative algorithm uses a fast first-fit algorithm, but produces bad page break with a higher probability. The quality algorithm is the same as the algorithm, except for two column content. <\explain> <|explain> This parameter specifies how much stretchable spaces may be extended or reduced in order to fill pages which are too short or too long. A page flexibility of allows spaces to be stretched to their minimal and maximal values. A page flexibility of prevents spaces to be stretched. For other values of the behaviour is linear. <\explain> <|explain> In the case when it is very hard to find good page breaks, this parameter specifies an additional amount of space by which a page is allowed to be reduced. <\explain> <|explain> In the case when it is very hard to find good page breaks, this parameter specifies an additional amount of space by which a page is allowed to be extended. <\explain> <|explain> This environment variable, which is initialized using , specifies how pages are rendered on the screen. The following values are available: <\description> >Page breaks are visually indicated on the screen. This mode is useful for ajusting the final version of a document before printing or sending it to a publisher. However, the use of this mode slows down the editor since every modification in the document triggers the page-breaking algorithm. Notice also that the mere selection of this mode does not imply the screen margins and page decorations to be as on paper. In order to previsualize a document in a fully realistic way, you should also set and . >The paragraph width is the same as on paper, but page breaking is disabled. This mode is most useful during the editing phase of a document which will ultimately be printed out. It combines a reasonable editing speed with realistic line breaks. >The paragraph width is as large as possible so as to fit into the current window and page breaking is disabled. This setting, which makes optimal use of the available space on your screen, is useful for documents which are not intended to be printed out. It may for instance be selected when using as a browser or as an interface to computer algebra systems. <\explain> <|explain> In mode, this environement variable contains the width of the screen. <\explain> <|explain> In mode, this environement variable contains the height of the screen. <\explain> <|explain> This flag specifies whether the screen margins are manually specified by the user, or whether they are the same as on paper. <\explain> <|explain> When is , then these environment variables determine the margins which are to be used for rendering on the screen. <\explain> <|explain> This flag determines whether the page headers and footers should be visible on the screen. When set to , it should be noticed that the headers and footers are not always correctly updated when editing. In the case when you suspect them to be wrong, refreshing the display by scrolling down and up should display the correct values. The parameters for page margins are represented schematically at the left hand side in figure . One may either specify the paragraph width as a function of the left and right margins, or . The left and right margins may depend on whether the page number is odd or even. <\explain> <|explain> When is set to , then the paragraph width is determined automatically from the page size and the left and right margins. When set to , the left and right margins are determined as a function of the page size, the paragraph width, and . For compatability with /, it is also possible to set to , in which case the horizontal margins are determined from , and . The variable plays a similar role for the vertical margins. <\explain> <|explain> By default, the width and height of a page are automatically determined from the page type. When is set to , then the user may manually specify the page size using and . <\explain> <|explain> If is set to , then and specify the left margins for odd and even pages. If is , then these values are computed as a function of the page size, the paragraph width, and . When and are set to , then a nice default left margin is determined as a function of the specified page type. <\explain> <|explain> If is set to , then specifies the right margin for odd pages. The right margin for even pages is given by the formula <\equation*> >+>-> If is or when is set to , then the right margin is determined in a similar way as the left margin. <\explain> <|explain> If is set to , then the left margins for odd and even pages are determined from the page size, paragraph width and the margin shifts using the formulas <\eqnarray*> >>||>->|2>+>>>|>>||>->|2>+>>>>> The right margin is always taken to be such that the paragraph width and the left and right margins sum up to the page width. <\quote-env> <\big-figure||ps>|0.5w|0.5h||>> Schematic representation of the layout of pages. On the left hand side, the parameters , , and respectively correspond to the left, right, top and bottom margins, and corresponds to the paragraph width. On the right hand side, , , and correspond to the header, footer, footnote and marginal note separations, to the width of marginal notes, and to the length of the footnote bar. <\explain> <|explain> These environment variables contain the header and footer texts for odd and even pages. <\explain> <|explain> These parameters determine the space between the main text and page headers and footers. They correspond to the and distances at the right hand side of figure . <\explain> <|explain> The separation between the main text and footnotes, the distance in figure . <\explain> <|explain> The length of the foornote bar. <\explain> <|explain> The separation between the main text and floating objects. <\explain> <|explain> The separation between marginal notes and the main text (not implemented yet). <\explain> <|explain> The width of marginal notes (not implemented yet). >