_{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
  

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.
• 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.
• An indented line continues the path of the line above it.
• Writing a key again replaces it. Writing into an object merges.
• a,b writes the same value under a and under b.
• 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

A leaf with lines indented under it is a multiline string. The lines under it are the value: each starts one tab deeper than the key's line and is taken verbatim from there, so 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. A line indented under a line of several leaves is an error, since no leaf can claim it.

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 and trailing tabs, 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) 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).

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.