In the fields of standard song repertoire and popular music, sheet music has for many years included a vocal line with piano accompaniment (which sometimes includes the vocal line), and graphically-represented e-chords above the vocal line, for either guitar or ukulele.
Many online versions of songs with chords are represented with a symbol above a lyric line which come with chord dictionaries that we shall refer to find out how to play e-chords. In the Jazz and Popular idioms, freedom in chord voicings is encouraged and expected, and notation of e-chords in this area tends to be with textual chord symbols – Cma or Cmaj for C major, Gmi or Gmin for G minor, etc.
This leaves the player free to choose inversions and voicings of the e-chords appropriate to their interpretation and style, and the e-chords can also be used as the basis for the player to create solo and improvisational melody lines as developments of the song or piece.
This method of e-chords notation has the advantage of not being instrument-specific; a guitarist, pianist, or any other chordal instrumentalist, as long as they know the chords on their own instrument, can read these charts with e-chords equally well as any other. Many e-chords found online tend to feature popular music and standard songs, and are typically presented with e-chord names above a lyric line, the duration of each e-chord in the ‘chord sequence’ being represented broadly by their position over a particular word or phrase in the lyric, rather than being given a note value – half note, quarter note – or duration expressed in parts of a bar – half bar, quarter bar, and so on.
Chordal ‘dictionaries’ tend to spell out the notes of e-chords in various inversions and flavours, and, as their name would suggest, are reference pages. One can find a lot of songs by artists in many different genres, allowing players of all levels to build their repertoire.