_{Logo made with PowerRP. Open it in PowerRP to edit it (source: assets/doc.json).}

dtab

Delta Tab. Config files made of tab-separated paths. One line is one path into a tree, and later lines are deltas on top of earlier ones. Try it in your browser: dtab on the left, JSON on the right.

objects	l1,l2 light
deltas	l1	position
	x 1	y .5	z -2

import dtab
dtab.parse(open("scene.dtab").read())
# {'objects': {'l1': 'light', 'l2': 'light'},
#  'deltas': {'l1': {'position': {'x': '1', 'y': '.5', 'z': '-2'}}}}

Why

• Less to look at. No braces, quotes, or commas between values. A file with its tabs aligned reads like pseudocode, and is easy to write by hand, even on paper.

• Simple. Six rules, one pass, about 70 lines per implementation.

• Everything is addressable. There are no lists, so every value has a path: config.deltas.l1.position.x with EasyDict in Python or plain property access in JavaScript, brackets for keys like file.json.

• You choose the shape. Lines stack, and c,d writes one value under several keys, so the same tree can be written wide, deep, or on one line, trading horizontal space for vertical. These are the same file:

  a	b	c x
  a	b	d x
  

  a
  	b
  		c x
  		d x
  

  a	b	c,d x
  

  A long list goes one key per line, the comma at the end of each saying it goes on:

  servers	alpha,
  	beta,
  	gamma	port 80
  

Rules

• Tabs separate the steps of a path. deltas l1 position walks three keys down. Several tabs in a row count as one, so you can align columns. Trailing tabs outside string bodies are ignored.
• An entry with a space is key value. It sets the key and stays at the same level, so x 1 y .5 sets two keys.
• Deeper lines belong to the last non-comment entry: children for an object, text for a leaf.
• Writing a key again replaces it. Writing into an object merges.
• a,b writes the same value under a and under b. Spaces, tabs or a line break may follow the comma, so a, b, and a, at the end of a line with b on the next, are the same list. A key must follow the comma: a comment cannot stand there.
• An entry that starts with a space is a comment.
• A leaf with lines indented under it is a multiline string. See below.

Every value is a string. Cast the ones you need. A key is any run of letters, digits, _, ., - and /, so file.json, 2026-09-07, assets/logo and 0 are keys. Keys that happen to be identifiers work as attributes (config.deltas.l1 with EasyDict and friends); the rest are reached with brackets (config["file.json"]).

Multiline strings

When the last non-comment entry is a leaf, deeper lines replace its value with a multiline string. Earlier entries keep their values. The body starts one tab past the header line's leading indentation and is taken verbatim from there. Tabs and deeper indentation inside are part of the value. This is the only way to put a tab in a value. Blank lines inside are kept, trailing ones dropped.

query sql	 a comment may follow the tag
	SELECT name, age
	FROM users
	WHERE age > 30

The leaf's own text is a tag that tells editors which language to highlight, and it is not part of the value. Any text will do, txt or nothing at all (prompt with a trailing space) for plain text. Unknown tags are plain text, never an error. For example:

hello world	moose meat
	world happy

This gives {"hello": "world", "moose": "world happy"}: moose is last, so the text belongs to it.

These forms both give {"A": {"B": {"code": "Some Code Here"}}}:

A	B	code py
	Some Code Here

A	B
	code py
		Some Code Here

Trailing tabs after B or code py change nothing. A space is different: B is an empty leaf, not an object key.

Install

• Python: pip install dtab then import dtab
• JavaScript: npm install deltatab then const dtab = require('deltatab'), or <script src="https://cdn.jsdelivr.net/npm/deltatab/dtab.js"> for window.dtab
• Vim: Plugin 'RyannDaGreat/dtab' (Vundle) or Plug 'RyannDaGreat/dtab' (vim-plug), or paste dtab.vim into your vimrc. Highlights *.dtab, flags bad keys, gives the file a Δ icon in NERDTree if vim-devicons is installed, :DtabPreview opens a split showing the tree as JSON that follows your edits (needs +python3), and J joins the line below with a tab (deep form to wide form), or with a space after a comma, whenever that keeps the tree the same.
• VS Code: search "dtab" in Extensions, or code --install-extension RyannDaGreat.dtab. Highlighting, a Δ file icon, and a live JSON preview of the file beside it (the preview button in the title bar, or Cmd+K V).
• Monaco, Shiki and other TextMate hosts: npm install deltatab includes the TextMate grammar, deltatab/vscode/syntaxes/dtab.tmLanguage.json. For Monaco, await highlight(monaco, {wasm: fetch(onigWasmUrl), grammars: {'source.sql': sqlGrammar}}) from deltatab/monaco.mjs colors a registered dtab language the way VS Code does, multiline-string headers included. It needs vscode-textmate, vscode-oniguruma, and 'semanticHighlighting.enabled': true in the editor options.
• Claude Code, Codex, Cursor and other agents: npx skills add RyannDaGreat/dtab installs a skill that teaches the agent the rules (skills/dtab/SKILL.md, in the Agent Skills format they all read).

API

• parse(text) returns nested dicts (Python) or plain objects (JavaScript). Raises on an invalid key, with the line number.
• stringify(tree) writes the tree back out, one key per line.
• Command line: dtab scene.dtab prints the tree as JSON.