This very important environment variable determines the current mode. There are four possible values: text (text mode), math (mathematical mode), prog (programming mode) and src (source mode). The behaviour of the editor (menus, keystrokes, typesetting, etc.) depends heavily on the mode. For example, the following code may be used in order to include a mathematical formula inside text:

Some other environment variables (mainly the language and the font) also depend on the current mode (in this context, the source mode always behaves in a similar way as the text mode). During copy&paste and search&replace operations, TeXmacs tries to preserve the mode.

A second major environment variable is the current language. In fact, there are three such environment variables: one for each mode. The language in which content is written is responsible for associating a precise semantics to the content. This semantics is used for different purposes:

• The language may specify rules for typesetting content. For instance, the text language specifies punctuation and hyphenation rules. Similarly the mathematical language containns spacing information for mathematical operators.
• Several editing operations depend on the current language: when performing a search or replace operation, TeXmacs is both mode and language sensitive. Similarly, the text language determines the dictionary to use when spell-checking the document.

• The language controls (among other parameters like the mode and the document format) the way content is being converted from one context to another.

  Currently, no real language-dependent conversions have been implemented yet. But in the future one may imagine that copying a piece of English text to a document written in French will perform an automatic translation. Similarly, a mathematical document might be converted from infix to postfix notation.

• The programming language determines the current scripting language in use. Other scripting languages than Scheme are currently only used for interactive sessions, but primitives like extern and mutator might become language-sensitive in the future.

At the moment, the current language is mainly used as a hint for indicating the semantics of text: it is not required that a text written in English contains no spelling errors, or that a formula written in a mathematical language is mathematically or even syntactically correct. Nevertheless, the editor is intended to enforce correctness more and more, especially for mathematics.

The language may be specified globally for the whole document in Document→Language and locally for a piece of text in Format→Language.

This environment variables is used in addition to the prog-language variable in order to determine a concrete implementation as well as a particular instance of the current programming language. For instance, in case of the Maxima language, different implementation may be used fooor the underlying Lisp. Similarly, one may wish to run two different instances of Maxima in parallel.

This variable determines the magnification which is applied to all content. Magnifications bigger than one are typically useful for presentations (from slides or from a laptop):

The magnification should not be confused with the font size: contrary to the magnification, the font size may also affect the shapes of the glyphs. The magnification is usually specified for the entire document in Document→Magnification.

The background color for your document, as specified in Document→Color→Background.

The current foreground color of text and graphics, as specified in Document→Color→Foreground or Format→Color.

This flag determines whether we are editing normal text or a style-sheet. The source tree or preamble mode may be selected in Document→View→Edit source tree.

This variable controls the rendering of informative flags, which are for instance used to indicate the locations of otherwise invisible labels or typesetting directives. The info-flag may take the values none, short and detailed:

Usually, the rendering of informative flags is specified document-wide in Document→View→Informative flags.

These variables control the main name of the font, also called the font family. For instance:

Similarly, TeXmacs supports various mathematical fonts:

This variable selects a variant of the major font, like a sans serif font, a typewriter font, and so on. As explained above, variants of a given font are designed to mix well together. Physically speaking, many fonts do not come with all possible variants (sans serif, typewriter, etc.), in which case TeXmacs tries to fall back on a suitable alternative font.

Typical variants for text fonts are rm (roman), tt (typewriter) and ss (sans serif):

In maths mode, a distinction is made between the mathematical variants mr (roman), mt (typewriter) and ms (sans serif) and textual variants rm (roman), bf (bold), etc. In the first case, variables and operators are usually rendered in a different slant, contrary to the second case:

The font series determines the weight of the font. Most fonts only provide regular and bold font weights. Some fonts also provide light as a possible value.

The font shape determines other characters of a font, like its slant, whether we use small capitals, whether it is condensed, and so on. For instance,

The base font size is specified in pt units and is usually invariant throughout the document. Usually, the base font size is 9pt, 10pt, 11pt or 12pt. Other font sizes are usually obtained by changing the magnification or the relative font-size.

The real font size is obtained by multiplying the font-base-size by the font-size multiplier. The following standard font sizes are available from Format→Size:

From a mathematical point of view, the multipliers are in a geometric progression with factor sqrt₄ (2). Notice that the font size is also affected by the index level.

The rendering quality of raster fonts (also called Type 3 fonts), such as the fonts generated by the Metafont program is controlled through its discretization precision in dots per inch. Nowadays, most laser printers offer a printing quality of at least 600dpi, which is also the default dpi setting for TeXmacs. For really high quality printing, professionals usually use a precision of 1200dpi. The dpi is usually set once and for all for the whole document.

The index level increases inside certain mathematical constructs such as indices and fractions. When the index level is high, formulas are rendered in a smaller font. Nevertheless, index levels higher than 2 are all rendered in the same way as index level 2; this ensures that formulas like

remain readable. The index level may be manually changed in Format→Index level, so as to produce formulas like

This environement variable controls whether we are in display style or not. Formulas which occur on separate lines like

are usually typeset in display style, contrary to inline formulas like

are typeset in a smaller font. You may override the default settings using Format→Display style.

By default, formulas like a + ⋯ + z are typeset using a nice, wide spacing around the + symbol. In formulas with scripts like ⅇ^{a + ⋯ + z} + ⅇ^{α + ⋯ + ζ} the readability is further enhanced by using a more condensed spacing inside the scripts: this helps the reader to distinguish symbols occurring in the scripts from symbols occurring at the ground level when the scripts are long. The default behaviour can be overridden using Format→Condensed.

For a high quality typesetting of fraction, it is good to avoid subscripts in numerators to descend to low and superscripts in denominators to ascend to high. TeXmacs therefore provides an additional environment variable math-vpos which takes the value 1 inside numerators, −1 inside denominators and 0 otherwise. In order to see the effect the different settings, consider the following formula:

In this example, the grouping is necessary in order to let the different vertical positions take effect on each a

This environment variable specifies the alignment of the different lines in a paragraph. Possible values are left, center, right and justify:

This parameter controls the quality of the hyphenation algorithm. Possible values are normal and professional. The professional hyphenation algorithm uses a global algorithm on the entire paragraph, whereas the normal one uses a faster first-fit algorithm.

This environment variable controls the width of paragraphs. By default, it is automatically determined as a function of the page (or screen) size and margins.

These environment variables specify absolute left and right margins for the paragraph, with respect to the default left and right margins (which are determined as a function of the page layout). For instance:

Environments like itemize and quote-env which maybe nested usually compute new margins as a function of the old values by adding or subtracting some space:

The par-first parameter specifies the additional indentation which is used for the first line of the paragraph. The aim of first indentations is to indicate the starts of new paragraphs. An alternative technique is the use of vertical whitespace.

The sum of the font size and par-sep determines the ideal distance between two successive base lines in a paragraph (also called the “base line skip”). Of course, when the lines contain large boxes, then this distance may need to be increased. When 1fn for par-sep, one may for instance produce documents with a double interline space:

In the case when two successive lines use different base line skips, then the maximal value is used in order to compute the ideal distance between their baselines. This allows for a reasonable spacing when the font size is changed from one paragraph to another:

This parameter corresponds an additional stretchable amount of whitespace between successive lines in a paragraph. Setting par-line-sep to a small stretchable value which defaults to 0 allows the page breaker to correctly stretch pages which contain a very long textual paragraph. Indeed, par-line-sep vanishes, then the height of a textual paragraph is of the form a + b n, where a and b are constants and n is the number of lines. There is no reason why the usable height of a page should be of this form.

The par-par-sep parameter specifies the amount of vertical whitespace which separates two successive paragraphs. This space is determined in stretchable length units. By default, TeXmacs does not use any whitespace between successive paragraphs, except when no nice page breaks could be found (this explains the use of the fn* length unit). Starts of new paragraphs are rather indicated through the use of first indentations (see table ?).

In the case when two successive paragraph use different paragraph separations, then the maximum of the two is taken. In fact, the par-par-sep length is added to both the vertical spacing before and the vertical spacing after the paragraph.

When a paragraph contains several exceptionally large boxes, then TeXmacs attempts to “shove successive lines into another” as long as none of the boxes collide:

As soon as the horizontal distance between two large boxes is less than par-hor-sep, then they are considered to be in collision. In that case, the vertical distance between them must be at least par-ver-sep. Also, the amount of showing never exceeds 1ex.

When using an interline space of 1.5 or 2, the default value of par-ver-sep allows the user to type larger formulas in the text while preserving a uniform layout. When using a small par-sep and a large par-ver-sep, the distance between two successive lines remains small, except when their contents are horizontally close. This may for instance be used to reduce the space between a short like followed by a centered equation.

This parameter controls the amount of vertical space between successive footnotes.

This environment variable specifies the number of columns into which the text is being typeset. Different numbers of columns may be used successively in the same document.

This environment variable specifies the amount of horizontal whitespace which separates different columns in multi-column mode.

Specify the size of a page when printing out. Most standard formats are available in Document→Page→Size. By default, the paper size is the one of your printer (the default printer settings may be changed in Edit→Preferences→Printer). When the page-type is set to user, then the page size is given by page-width and page-height.

The orientation of pages can be either portrait or landscape.

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 label and page-ref primitives. Nevertheless, the page-nr variable can be used in the macros which render page headers and footers.

This environment variable really contains the macro which is used for rendering the page-number. By default, it renders page-nr. The macro takes no arguments. In order to simulate a document whose first page number os 123, one may redefine

This parameter specifies the page breaking algorithm. The default optimal algorithm takes into account the global document and tries hard to avoid bad page breaks. The alternative sloppy algorithm uses a fast first-fit algorithm, but produces bad page break with a higher probability. The medium quality algorithm is the same as the optimal algorithm, except for two column content.

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 1 allows spaces to be stretched to their minimal and maximal values. A page flexibility of 0 prevents spaces to be stretched. For other values of page-flexibility the behaviour is linear.

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.

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.

This environment variable, which is initialized using Document→Page→Type, specifies how pages are rendered on the screen. The following values are available:

paper

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 Document→View→Page layout→Show header and footer and Document→View→Page layout→Margins as on paper.

papyrus

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.

automatic

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 TeXmacs as a browser or as an interface to computer algebra systems.

In automatic mode, this environement variable contains the width of the screen.

In automatic mode, this environement variable contains the height of the screen.

This flag specifies whether the screen margins are manually specified by the user, or whether they are the same as on paper.

When page-screen-margin is true, then these environment variables determine the margins which are to be used for rendering on the screen.

This flag determines whether the page headers and footers should be visible on the screen. When set to true, 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.