Root work
Work that is not based on another work.
Adaptation
Work that is based on another work.
Example: Adaptation Acuarela azul is the translation in Spanish of the root work Acquerello in blue
Note: Improvisation, or additional music and/or lyrics composed during the performance is very common in jazz, folk and roots music. However, because this improvisation is not defined in advance, we consider these performances versions of the root work, not of a newly composed adaptation.
Combined Adaptation
An adaptation that takes music from one work, and lyrics from another work, and has no additional writing credits.
Example: New Britain combines the music from St. Mary's and the lyrics from Hymn XLI [poem] .