Characteristics of Collected Works:

• Focus on a genre, time period, geographical area, or composer.
  • Other names: Historical Sets, Denkmaler, Monuments of Music; begins "01" in the Dickinson Music Library
  • The complete works of a single composer are also called "collected works," "complete editions" or "Gesamtausgabe" and aim to present a complete repertory.  Begins "05" in the Dickinson Music Library
• Valuable for the study of original versions of past music.
• Prepared on the basis of a critical evaluation of all known primary sources.
• Designed to present the most authoritative authentic version of its contents to most accurately reflect the composer's intentions.
• Editorial material clearly distinguished from the original. 
• Often are issued over years or decades. 
• Includes critical apparatus:
  • Describes the documentation of variants and designates as editorial whatever is added to the sources.

Critical editions differ from "performing" or "practical" editions in the following ways:

• The ‘practical’ or ‘performance’ editions usually are produced from unstated or secondary sources.
• They may incorporate additions or changes designed to help the modern performer.

For more detailed information see:

•  Historical editions from Grove Music Online.
•  Editions, historical from Harvard Dictionary of Music.