I have played flamenco guitar for 47 years. When I was learning to play, the current versions of the forms could be traced back to a few virtuosos who came on the scene as early as 1905 or thereabouts. Every form is played as a series of sections that are distinct in melody and are sandwiched between more or less standard rhythmic sections characteristic of the form. The melodic sections are called "falsetas". The sections are played in whatever order a player chooses and players spend spare time trying to invent new falsetas or modifying old ones. Most players know the genealogy of their falsetas to some extent, but anything that is older than a couple of generations is usually of unknown origin.

Lore has it that great flamenco guitarists invent falsetas on the fly during performance. This is nonsense. But that's another story. Hardly any guitarist can read music and/or uses any kind of notation to commit falsetas to paper.

In the cante (song) the verses (letras) and the melodies are generally very old though most are associated with the name of the originator.

Through the 1950s it was expected that players would play mostly traditional things with minor additional innovations. The falsetas of a particular player did not usually evolve from one recording to the next, and, indeed, players had favorite falsetas that they played for years.

But as soon as recording industry moguls got involved all that changed. Nowadays they are claiming copyright on everything that is recorded, even the traditional portions that have been played since antiquity. Guitarists such as Paco de Lucia are pushed and prodded to innovate, and he has said publicly that the creation of new material is the most difficult part of what he does in this modern environment. Yet even his innovations (when he plays flamenco instead of the bastardized watered down stuff he mostly plays these days) contain traditional resolution phrases and rhythmic sections that define the forms and are ancient anonymous creations.

Spanish copyright has gone crazy locking up the public domain along with the new in recent years.