Among Senor Obregon’s list of ‘Effects on the Spanish Guitar’ (1904):

When I posted this on Facebook, Mark Delpriora commented that Pascual Roch used these same descriptions in his method book, published 17 years later. Both Roch and Obregon were students of Francisco Tarrega, and so perhaps we can surmise that they learnt these ‘effects’ from the maestro!