Artificial Fonts (The GNU Troff Manual)

#### 5.19.7 Artificial Fonts

There are a number of requests and escape sequences for artificially creating fonts. These are largely vestiges of the days when output devices did not have a wide variety of fonts, and when `nroff` and `troff` were separate programs. Most of them are no longer necessary in GNU `troff`. Nevertheless, they are supported.

Escape sequence: `\H`'``height``'`` ¶
Escape sequence: `\H`'```+`height``'`` ¶
Escape sequence: `\H`'```-`height``'`` ¶
Register: `\n[.height]` ¶

  Change (increment, decrement) the height of the current font, but not the width. If height is zero, restore the original height. Default scaling unit is ‘`z`’.

  The read-only register `.height` contains the font height as set by `\H`.

  Currently, only the `-Tps` and `-Tpdf` devices support this feature.

  `\H` doesn’t produce an input token in GNU `troff`. As a consequence, it can be used in requests like `mc` (which expects a single character as an argument) to change the font on the fly:

      .mc \H'+5z'x\H'0'

  In compatibility mode, `gtroff` behaves differently: If an increment or decrement is used, it is always taken relative to the current type size and not relative to the previously selected font height. Thus,

      .cp 1
      \H'+5'test \H'+5'test

  prints the word ‘`test`’ twice with the same font height (five points larger than the current font size).

Escape sequence: `\S`'``slant``'`` ¶
Register: `\n[.slant]` ¶

  Slant the current font by slant degrees. Positive values slant to the right. Only integer values are possible.

  The read-only register `.slant` contains the font slant as set by `\S`.

  Currently, only the `-Tps` and `-Tpdf` devices support this feature.

  `\S` doesn’t produce an input token in GNU `troff`. As a consequence, it can be used in requests like `mc` (which expects a single character as an argument) to change the font on the fly:

      .mc \S'20'x\S'0'

  This escape is incorrectly documented in the AT&T `troff` manual; the slant is always set to an absolute value.

Request: `.ul` [lines] ¶

  The `ul` request normally underlines subsequent lines if a TTY output device is used. Otherwise, the lines are printed in italics (only the term ‘underlined’ is used in the following). The single argument is the quantity of input lines to be underlined; with no argument, the next line is underlined. If lines is zero or negative, stop the effects of `ul` (if it was active). Requests and empty lines do not count for computing the number of underlined input lines, even if they produce some output like `tl`. Lines inserted by macros (e.g., invoked by a trap) do count.

  At the beginning of `ul`, the current font is stored and the underline font is activated. Within the span of a `ul` request, it is possible to change fonts, but after the last line affected by `ul` the saved font is restored.

  This number of lines still to be underlined is associated with the environment (see Environments). The underline font can be changed with the `uf` request.

  The `ul` request does not underline spaces.

Request: `.cu` [lines] ¶

  The `cu` request is similar to `ul` but underlines spaces as well (if a TTY output device is used).

Request: `.uf` font ¶

  Set the underline font (globally) used by `ul` and `cu`. By default, this is the font at position 2. font can be either a non-negative font position or the name of a font.

Request: `.bd` font [offset] ¶
Request: `.bd` font1 font2 [offset] ¶
Register: `\n[.b]` ¶

  Embolden font by overstriking its glyphs offset by offset units minus one.

  Two syntax forms are available.

  - Imitate a bold font unconditionally. The first argument specifies the font to embolden, and the second is the number of basic units, minus one, by which the two glyphs are offset. If the second argument is missing, emboldening is turned off.

    font can be either a non-negative font position or the name of a font.

    offset is available in the `.b` read-only register if a special font is active; in the `bd` request, its default unit is ‘`u`’.

  - Imitate a bold form conditionally. Embolden font1 by offset only if font font2 is the current font. This request can be issued repeatedly to set up different emboldening values for different current fonts. If the second argument is missing, emboldening is turned off for this particular current font.

    This affects special fonts only (either set up with the `special` command in font files or with the `fspecial` request).

Request: `.cs` font [width [em-size]] ¶

  Switch to and from constant glyph space mode. If activated, the width of every glyph is width/36 ems. The em size is given absolutely by em-size; if this argument is missing, the em value is taken from the current font size (as set with the `ps` request) when the font is effectively in use. Without second and third argument, constant glyph space mode is deactivated.

  Default scaling unit for em-size is ‘`z`’; width is an integer.