Music-theory references
Open Music Theory and Robert Hutchinson’s Music Theory for the 21st-Century Classroom provide the main factual checks for triads, seventh chords, written intervals, major and minor scales, key signatures and diatonic harmony. Open Music Theory’s chapter on diatonic modes supports the comparisons on one tonic.
The examples here are independently constructed: C-major inversions, one-note quality changes, short I–IV–V–I sequences and scale traces. Publisher prose, song excerpts, lesson diagrams and recordings have not been copied into the articles.
| Reference family | Used to check |
|---|---|
| Open Music Theory | Triad structure; major-scale pattern and spelling |
| Music Theory for the 21st-Century Classroom | Minor forms; seventh chords; inversion; enharmonic names; intervals; key signatures; meter |
| Open Music Theory: Diatonic modes | Same-tonic modal formulas and familiar aliases |
| Fender standard-tuning article | E–A–D–G–B–E and adjacent-string relationships |
Browser and accessibility references
The WHATWG storage specification explains browser-local storage and failure conditions. The W3C Web Audio draft informs playback behavior. W3C accessibility explanations inform keyboard and visible-focus goals.
These references describe platform behavior and standards; they are not evidence that every browser, device or assistive technology has been tested with ChordLilt. Application tests and actual rendering checks are separate work.
How a factual check is recorded
Each reviewed page names its relevant sources. The editorial record summarizes what each source was used to verify and keeps a fingerprint of the reviewed copy. A content change must be checked again rather than inheriting a review marker from older text.
Music pages also include exact formulas, notes and examples that can be checked independently. A citation should support the nearby definition or convention, not stand in for checking the arithmetic or the displayed result.
Licenses and attribution
Open Music Theory identifies its general license as Creative Commons Attribution–ShareAlike 4.0, with exceptions for separately credited material. Music Theory for the 21st-Century Classroom identifies the GNU Free Documentation License 1.2 or later in its colophon. Other linked resources have their own terms.
Those licenses describe the referenced works. ChordLilt does not repackage their text or artwork, and a factual reference does not imply an endorsement or a broader permission to reuse their assets. The source entries below record the license or the limits on assumed reuse.
Read access notes honestly
A publisher-hosted search excerpt can support a limited factual check, but it is not recorded as a complete downloaded document. Sources that could not be retrieved were replaced with accessible primary material where possible.
The local product contract records the intended feature scope; it is not an external music textbook or proof of finished browser behavior. Contact availability and privacy details still depend on the actual public operator and hosting configuration.
Open Music Theory: Triads
Triad quality is determined by intervals above a root. Major and minor triads keep a perfect fifth and differ in the third. Written thirds preserve alternating letter names.
CC BY-SA 4.0 except separately credited material; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Open Music Theory: Major scales
The major-scale steps are 2,2,1,2,2,2,1 semitones. Key signatures and scale degrees describe written notes; a seven-note diatonic spelling uses consecutive letters.
CC BY-SA 4.0 except separately credited material; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Minor scales
Natural minor has lowered third, sixth and seventh relative to the parallel major. Harmonic minor raises the seventh; the traditional melodic form raises sixth and seventh ascending and uses natural minor descending.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Introduction to seventh chords
A seventh chord extends a triad with a seventh above its root. Major, dominant, minor, half-diminished and diminished families have different interval patterns; their names are not interchangeable.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Diatonic chords in major
Triads stacked from a major scale have major, minor, minor, major, major, minor and diminished qualities in scale-degree order.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Major key signatures
Key signatures follow orders of sharps or flats. Fifth-related keys differ by one signature accidental. Several conventional written keys are enharmonically equivalent, so twelve pitch classes do not imply only twelve possible key spellings.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Enharmonic notes
Different written notes can share a piano key. Their spelling remains meaningful when describing a scale degree, chord member or named interval.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Augmented and diminished intervals
An augmented interval is one semitone larger than a perfect or major interval; a diminished interval is one semitone smaller than a perfect or minor interval. Letter distance remains part of the interval name.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Standard tuning: how EADGBE came to be
Standard guitar tuning runs E A D G B E from low to high, with a major third between G and B and perfect fourths between the other neighboring strings.
Copyrighted publisher article; factual reference only, no copied wording or media. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Web Audio API 1.1
The 22 September 2026 Working Draft describes audio contexts, user-activation constraints and scheduled source start/stop times. This is an API reference, not evidence that every browser configuration has been tested.
W3C permissive document license; reference only, no specification text reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
ChordLilt product contract
The approved scope specifies local deterministic tools, explicit playback, twelve chord qualities, standard guitar tuning, named local collections and SVG/PDF/JSON exports. Runtime behavior must separately pass application tests.
User-supplied requirements; original product copy written for this project. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Local product contract reviewed; no external publisher retrieval claimed; checked 2026-10-28.
HTML Standard: Web storage
Local storage belongs to the browser origin. Writes can fail, including when storage is blocked or quota is exhausted. Browser settings and clearing data can remove stored values.
WHATWG standard; factual reference only, no copied specification text. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Roman numerals of diatonic seventh chords
Roman numerals identify a scale degree and chord quality. Major-seventh, dominant-seventh, minor-seventh, half-diminished and diminished indications carry different interval meanings.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Inverted triads
A triad is in root position, first inversion or second inversion when its root, third or fifth respectively is in the bass. A slash symbol places the bass name after the slash.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Simple suspended chords
A sus2 chord uses a second in place of the third, and sus4 uses a fourth; both retain the perfect fifth. The same pitch-class set can support different root assumptions.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Modes and other scales
Modal interval patterns can be compared with major or natural minor on the same tonic. Ionian corresponds to major and Aeolian to natural minor; other diatonic modes alter characteristic scale degrees.
University teaching handout; no redistribution permission assumed; facts checked without copying the document. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Publisher-hosted PDF search text reviewed; authored 2018, not treated as a new 2026 publication; checked 2026-10-26.
Meter
Tempo describes pulse speed and can be expressed in beats per minute. Meter groups beats, and simple versus compound meter describes their usual divisions.
GNU Free Documentation License 1.2 or later, as stated in the publisher colophon; no text or figures reproduced. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher-hosted search text retrieved and reviewed; checked 2026-10-26.
Understanding WCAG 2.2: Keyboard
The informative explanation of criterion 2.1.1 describes keyboard access to functionality without requiring precisely timed keystrokes, except for functions whose underlying purpose requires a movement path. It does not certify this application.
W3C permissive document license; factual reference only, no copied specification text. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Understanding WCAG 2.2: Focus Visible
The informative explanation of criterion 2.4.7 describes a visible indicator for keyboard focus, allowing users to locate the currently focused control. It does not certify this application.
W3C permissive document license; factual reference only, no copied specification text. Definitions were checked; prose, examples and data were written or derived independently. No lesson artwork, song excerpt or recording is included.
Access record: Relevant publisher text retrieved and reviewed; checked 2026-10-26.
Current inversion reference check
The inversion chart was checked against the opened Puget Sound explanation of root, bass and slash symbols. Open Music Theory was also consulted through its chapter navigation and search excerpt; detailed follow-up requests were blocked. This access limitation is recorded with the source rather than described as a complete new chapter reading.
Font licenses are available from the Sources page.
Sources and methods
Open Music Theory: Triads
Open Music Theory / VIVA · 2026-10-26
Open Music Theory: Major scales
Open Music Theory / VIVA · 2026-10-26
Minor scales
Robert Hutchinson / University of Puget Sound · 2026-10-26
Introduction to seventh chords
Robert Hutchinson / University of Puget Sound · 2026-10-26
Diatonic chords in major
Robert Hutchinson / University of Puget Sound · 2026-10-26
Major key signatures
Robert Hutchinson / University of Puget Sound · 2026-10-26
Enharmonic notes
Robert Hutchinson / University of Puget Sound · 2026-10-26
Augmented and diminished intervals
Robert Hutchinson / University of Puget Sound · 2026-10-26
Standard tuning: how EADGBE came to be
Fender · 2026-10-26
Web Audio API 1.1
World Wide Web Consortium · 2026-10-26
ChordLilt product contract
User-supplied project requirements · 2026-10-28
HTML Standard: Web storage
WHATWG · 2026-10-26
Roman numerals of diatonic seventh chords
Robert Hutchinson / University of Puget Sound · 2026-10-26
Inverted triads
Robert Hutchinson / University of Puget Sound · 2026-10-26
Simple suspended chords
Robert Hutchinson / University of Puget Sound · 2026-10-26
Open Music Theory: Diatonic modes
Chelsey Hamm / Open Music Theory / VIVA · 2026-10-28
Meter
Robert Hutchinson / University of Puget Sound · 2026-10-26
Understanding WCAG 2.2: Keyboard
World Wide Web Consortium / Web Accessibility Initiative · 2026-10-26
Understanding WCAG 2.2: Focus Visible
World Wide Web Consortium / Web Accessibility Initiative · 2026-10-26
Inversion — Open Music Theory
Open Music Theory / VIVA Open Publishing · 2026-10-28