Parameters and Variables

Every engine parameter is an ordinary variable. Read one with \the\name (or bare \name), set one with \set name {value}, and use it in arithmetic with \calc{…}. Assignments are local…

Every engine parameter is an ordinary variable. Read one with \the\name (or bare \name), set one with \set name {value}, and use it in arithmetic with \calc{…}. Assignments are local to the current group unless made \global; \setlength / \addtolength are the LaTeX-named forms for the dimension-valued ones.

Dimensions accept any unit (pt, in, cm, mm, em, ex); a bare number is points. Glue is a natural size with optional plus/minus stretch and shrink (\set parskip {0pt plus 1pt}). The defaults below are the values a fresh document starts with.

Page and text area

Variable	Default	Meaning
`hsize`	`6.5in`	width of the text block (the line width)
`vsize`	`9in`	height of the text block (the page body)
`paperwidth`	`8.5in`	physical sheet width (LaTeX/pdfTeX; classic TeX has none)
`paperheight`	`11in`	physical sheet height
`hoffset`	`1in`	left margin — the text block’s x offset from the sheet corner
`voffset`	`1in`	top margin — the text block’s y offset from the sheet corner
`pageno`	`1`	the current page number (folio), advanced as pages ship
`topskip`	`10pt`	glue from the page top to the first baseline
`raggedbottom`	`0`	nonzero: pad short page bottoms with fil instead of stretching their glue

The far margins are whatever is left over: paperwidth − hoffset − hsize and likewise vertically. The \geometry primitive sets these as a group from margin/size options.

Running heads and feet

Variable	Default	Meaning
`headsep`	`0.25in`	gap from the bottom of the running header to the top of the body
`footskip`	`0.25in`	gap from the bottom of the body to the top of the running footer
`topmark`	`""`	the last `\mark` of the previous page
`firstmark`	`""`	the first `\mark` on the page being shipped
`botmark`	`""`	the last `\mark` on the page being shipped

A document supplies the header/footer content by defining headline / footline macros; \the\pageno inside them is always the shipping page’s number. The mark variables drive running heads that track the section a page covers.

Paragraph shape

Variable	Default	Meaning
`parindent`	`20pt`	first-line indent of a paragraph
`parskip`	`0pt plus 1pt`	vertical glue between paragraphs
`leftskip`	`0pt`	glue added at the left of every line
`rightskip`	`0pt`	glue added at the right of every line
`parfillskip`	`0pt plus 1fil`	glue that fills out a paragraph’s last line
`hangindent`	`0pt`	hanging-indent width (negative indents the right)
`hangafter`	`1`	apply the hanging indent after this many lines

Inter-line and inter-word spacing

Variable	Default	Meaning
`baselineskip`	`1.2 ×` font size	target distance between consecutive baselines
`lineskip`	`1pt`	baseline glue used when lines would otherwise be closer than `lineskiplimit`
`lineskiplimit`	`0pt`	the closeness threshold below which `lineskip` replaces `baselineskip`
`spaceskip`	font space	interword glue (reset when the font changes)
`xspaceskip`	`1.5 ×` font space	interword glue at a wider (sentence) space

Line breaking (Knuth–Plass)

Variable	Default	Meaning
`tolerance`	`200`	maximum acceptable line badness
`pretolerance`	`100`	first-pass tolerance, before hyphenation is tried
`hyphenpenalty`	`50`	penalty for breaking at a discretionary hyphen
`exhyphenpenalty`	`50`	penalty for breaking at an explicit hyphen
`linepenalty`	`10`	penalty charged per line, to prefer fewer lines
`adjdemerits`	`10000`	demerits for visually adjacent tight and loose lines
`emergencystretch`	`0pt`	extra per-line stretch in a final pass for paragraphs that will not justify

Page breaking

The page builder breaks by cost (badness + penalty); 0–9999 biases against a break here, 10000 forbids one, -10000 forces one.

Variable	Default	Meaning
`clubpenalty`	`10000`	against breaking after a paragraph’s first line (orphans)
`widowpenalty`	`10000`	against breaking before a paragraph’s last line (widows)
`interlinepenalty`	`0`	against breaking between any other two lines
`wrappenalty`	`10000`	against a break inside a wrapped figure’s band

Display math

Variable	Default	Meaning
`abovedisplayskip`	`0.83em plus/minus 0.17em`	glue set above a displayed formula
`belowdisplayskip`	`0.83em plus/minus 0.17em`	glue set below a displayed formula

Footnotes

Variable	Default	Meaning
`footnotesep`	`1em`	space above the footnote separator rule
`footnotesize`	`0.8`	footnote text size, as a fraction of the surrounding font
`footnoteno`	`0`	the footnote counter, advanced by each `\footnote`

Floats

Variable	Default	Meaning
`floatsep`	`0.85em`	space between two floats stacked in a page’s float area
`textfloatsep`	`1.4em`	space between the float area and the body text
`wrapsep`	`12pt`	gutter between a wrapped figure and the text flowing around it

Images

Variable	Default	Meaning
`imageScaling`	`1.0`	a global multiplier applied to placed image sizes
`imagessupported`	backend	read-only `1`/`0` flag: can this backend rasterize images?

A document can branch on imagessupported to choose an inline bitmap where it is available and a drawn fallback where it is not.

Frame and rule lengths

These have no engine default; the document package and the framing primitives read them when set, falling back to the LaTeX values shown.

Variable	Fallback	Meaning
`fboxsep`	`3pt`	padding between content and rule in `\fbox` / `\colorbox`
`fboxrule`	`0.4pt`	rule thickness for `\fbox` / `\fcolorbox`

Units

pt (the base unit, 1/72 in), in, cm, mm, em (the current font size), ex (its x-height).