Music Research - finding the score

Critical or Scholarly Editions – (Also sometimes known as "Study scores" or "Historical editions") Are based on scholarly evaluation and comparison of sources, taking into account variant readings.  Editors examine all available editions of a given work, including sketches, manuscripts, publisher’s proof copies, early printed editions, etc. to create the most scholarly edition they can.  

• Critical commentary is included that discusses any alterations in accidentals, notes, ornaments, and so forth.
• References are included to any manuscript sources available and also to research on whether the composer made changes to the original (such as notes or cuts, etc.).
• These editions are also sometimes called ‘complete works’ or ‘Gesamtausgabe’.