RSyntaxTree notation, on one page.

A tree is labeled brackets: [S [NP the cat] [VP sat]]. The label follows the
opening bracket; children follow the label. Parentheses are read as Penn
Treebank notation and converted: (S (NP the cat) (VP sat)) draws the same tree.

## What already means something

The characters that bite, first. A mistake the tool can see is refused with a
hint; everything below is taken silently, and the figure that draws is not the
figure that was meant.

- `<>` is one space and `<3>` is three, everywhere — never angle brackets.
  Where linguistics wants the brackets themselves, write ⟨ and ⟩ (U+27E8/9):
  SPR\t⟨<>NP<>⟩, 'hand⟨SUBJ,OBJ⟩'. A label written <NP> is refused with this
  advice; a stray <3> simply draws three spaces. No text face carries these
  two characters, so whatever the machine falls back to draws them — they
  will not quite match the letters beside them, and how far off they look
  depends on the fonts installed.
- A pair of hyphens underlines what stands between them: well-made-word draws
  "made" underlined. (A lone hyphen is refused with a hint.) Write `\-` for a
  hyphen — V\-bar, HEAD\-DTR — or set the hyphen option to literal.
- A raw space is safe in a one-line label and unreliable in a label that has
  `\n` or `\t` in it: there it can split a value that carries markup, and it
  breaks a nested #( ... #) matrix. Inside any label with columns, write a
  space as `<>`: 'a<>toy', not 'a toy'.
- A straight apostrophe is typeset as the curly ’ (U+2019).
- A backslash takes the character after it, whatever it is: \q draws q, and
  C:\path draws C:path. A backslash itself is \\.
- The prefixes of a label compose in one order, and only this one:
  `^` → `#`/`##`/`###` → `%` → `@color:`. So ^#%@red:NP is read whole, while
  @red:%NP leaves the % as a literal character and silently drops the shade.
- A rule name (for derivations) is written after the label's last `\t`, as in
  [S/NP\t>B ...], and needs the derivation option ON — with it off the name is
  drawn as a column. The name is taken out before markup runs, so `>` and `<`
  need no escaping there and `\>` would put the backslash in the figure. A
  label that also carries `\n` keeps all its columns instead.

## What there is

Structure:

| what                                   | how it is written |
|----------------------------------------|-------------------|
| a node with children                   | [S [NP the cat] [VP sat]] |
| a phrase under one leaf (triangle)     | [NP a toy] — one word, forced: [NP ^cats] |
| an invisible joint, to align leaves    | a label of only <>, as in [X [<> [Y y]] [Z z]] |
| a movement path (dashed)               | [S [NP a+1] [VP [V b] [NP c+1]]] |
| the same, with an arrowhead            | write +>1 on the end the arrow points at |
| an extra straight connector            | +-1 on two nodes; +->1 for an arrowhead |

Inside a label:

| what                                   | how it is written |
|----------------------------------------|-------------------|
| italic, bold, both                     | *x*, **x**, ***x*** |
| subscript, superscript                 | x_i_, x__2__ |
| small capitals                         | H___EAD___ |
| overline, underline, strikethrough     | =x=, -x-, ~x~ |
| a line break; a blank line             | a\nb (or a\ b); \n\n |
| columns, aligned down the label        | HEAD\t*verb*\nSPR\t⟨<>⟩ |
| a horizontal rule across the label     | a line of --- (or === for a double rule) |
| boxed, circled text                    | |1|, {2} — more than one character draws a capsule |
| empty and hatched boxes and circles    | ||, {}, |/|, {/} |
| bar and arrows as symbols              | --, ->, <-, <-> — bold with *...*, as in *->* |

Around a label:

| what                                   | how it is written |
|----------------------------------------|-------------------|
| square brackets, rectangle, bold       | #NP, ##NP, ###NP |
| a feature matrix as a value            | #(HEAD\tnoun#), nested to any depth |
| a whole label that is one matrix       | [#(CAT\tS#) [#(CAT\tNP#) Kim] [#(CAT\tVP#) sleeps]] |
| a region shade behind the subtree      | %NP, coloured: %@blue:NP |
| a colour                               | @red:NP, @#3af:NP, @#33aaff:NP (3 or 6 hex digits) |

An attribute-value matrix is columns plus an enclosure, and a value can be
another matrix — nested with #( ... #), never with square brackets, which are
read as tree structure:

    [#PRED\t'hand⟨SUBJ,OBJ⟩'\
      TENSE\tpast\
      SUBJ\t#(PRED\t'David'#)
    ]

Options (the command line spells them --like-this):

| option     | what it decides |
|------------|-----------------|
| format     | png, svg, pdf, tikz, json (the tree as structured data) |
| fontstyle  | sans, serif, mono, cjk |
| fontsize   | 6–26 |
| color      | modern, traditional, off, gray |
| linewidth  | every line's weight, 0.5–3.0, as a ratio of the font size |
| leafstyle  | auto, bar, nothing — what joins a node to its leaf |
| direction  | ttb, ltr, btt |
| mirror     | flip the finished layout, for RTL scripts |
| tidy       | off, symmetric, low, medium, high — how tightly subtrees pack |
| hspacing   | how far apart sisters sit, 0.5–3.0 |
| vheight    | how far apart levels sit, 0.5–5.0 |
| polyline   | draw each connector as two right angles rather than a slanted line |
| hide_default_connectors | draw no parent-to-child lines, leaving only the ones written with +-n — how a lattice or a network is drawn |
| transparent | leave the background clear instead of painting it white |
| derivation | one rule across the daughters, categorial-grammar style |
| hyphen     | markup (hyphens underline) or literal (hyphens are hyphens) |
| shear      | tilt the drawn figure: degrees, −45 to 45, positive leans the top right |
| shear_plane | the plane behind a sheared figure: on (grey), off, or a colour; never drawn on a transparent background |
| vmargin    | clearance between a label and its connectors, 0.1–1.0, the same above and below |

hspacing and vheight are named for the top-to-bottom layout, and follow the
tree rather than the page: with direction ltr, sisters stack downwards and
hspacing is what separates them, while vheight runs across.

The full manual explains each of these with figures, and every example in the
gallery is written out beside the figure it draws:

    https://yohasebe.github.io/rsyntaxtree/documentation
    https://yohasebe.github.io/rsyntaxtree/examples