5.1 Dimensiones geométricas del diseño

The text of a document usually occupies a rectangular area on the paper— the socalled type area or body. Above the text there might be a running header and below it a running footer. They can consist of one or more lines containing the page number; information about the current chapter, section, time, and date; and possibly other markers. If they are visually heavy and closely tied to the text, then these elements are considered part of the type area; this is often the case for running headers, especially when underlined. Otherwise, they are considered to belong to the top or bottom margins. This distinction is important when interpreting size specifications.

The fields to the left and the right of the body are also called margins. Usually they are left blank, but small pieces of text such as remarks or annotations — so-called marginal notes — can appear there.

In general one talks about the inner and outer margins. For two-sided printing, inner refers to the middle margins — that is, the left margin on recto (odd-numbered) pages and the right margin on verso (even-numbered) ones. For one-sided printing, inner always indicates the left margin. In a book spread, odd-numbered pages are those on the right-hand side.1

The size, shape, and position of these fields and margins on the output medium (paper or screen) and the contents of the running headers and footers are collectively called a page layout.

The standard LaTEX document classes allow document formatting for recto–verso (two-sided) printing. Two-sided layouts can be either asymmetrical or symmetrical (the LaTEX default). In the latter case the type areas of recto and verso pages are positioned in such a way that they overlap if one holds a sheet to the light. Also, marginal notes are usually swapped between left/right pages.

The dimensional parameters controlling the page layout are described and shown schematically in Figure 5.1 on the facing page.2 The default values of these parameters depend on the paper size. To ease the adjustments necessary to print on different paper sizes, the LaTEX class files support a number of options that set those parameters to the physical size of the requested paper as well as adjust the other parameters (e.g., ) that depend on them.

Table 5.1 on page 368 shows the paper size options known to standard LaTEX classes together with the corresponding page dimensions. Table 5.2 on page 369 presents the page layout parameter values for the letterpaper paper size option, the default when no explicit option is selected. They are identical for the three standard LaTEX document classes (article, book, and report). If a different paper size option is selected, the values may change. Thus, to print on A4 paper, you can simply specify