Some good suggestions here, and our goal should be to come up with something that is both simple to understand and to implement.
With this in mind, and after a great deal of soul-searching and experimentation, I would like to propose just two top-level headings: "Original Works" and "Arrangements and Transcriptions", as follows:
===
Original Work===
The category "Original Work" denotes the composition in the genre for which it was originally conceived (e.g. for orchestra, chorus, piano, etc.). If the "Original Work" was significantly revised or altered by the composer, or completed by others (still in the same genre), then appropriate sub-headings can be added, e.g.:
====1st version (1869)====
====3rd version (1880)====
====Completion by Nikolay Rimsky-Korskov, 2nd version (1906)====
====Completion by Hector Berlioz (1834)====
For the majority of cases this level will not be required, as the composition only exists in one version.
Within each category, the available editions should be listed chronologically, so the composer's manuscript might appear first, and modern computerised editions last.
If a score only exists for part of a work (and it isn't just a partial scan of a fuller work), then the level 5 heading ("=====") "Extracts" can be used, and placed after complete scores in the same category. Scores should be assumed to relate to the whole work, unless otherwise indicated by this heading.
The file descriptions (rather than new headings) should also consistenly indicate whether the PDF file relates to a "Complete Score" for the whole work, or just of a named or numbered extract.
===
Arrangements and Transcriptions===
All later versions of the work — whether by the composer or other hands — should be listed here. It would probably be most helpful to list these in descending order of instrumentation, i.e. orchestrations first, then vocal scores (for operas), chamber arrangements and piano transcriptions. Each arrangement should have its own heading, e.g.
====Arrangement for Orchestra (Ravel)====
====Vocal Score (composer/Smith)====
====Arrangement for violin with piano (composer)====
====Transcription for piano duet (Beethoven)====
The full names of the arrangers will appear in the description for each file, under "Editor", so surnames will suffice (but can be omitted if the arranger is unknown). Within each heading the arrangement should be chronological, as for the original work, with complete scores taking precedence over extracts.
The term "Transcription" is often used for a piano reduction of a piece, whereas "Arrangement" is taken to mean an orchestration of a smaller-scale piece. However, sometimes the opposite is understood, so we should use the terms consistently, or stick with "Arrangement" for both purposes.
As instrumental parts can (in theory) belong to a wide range of categories (i.e. full scores, vocal scores, arrangements), it seems logical to list them immediately after the edition from which they were derived, even if that has not yet been added independently.
The last important rule is that headings and sub-headings should not be used for empty categories. For example, if a page only has arrangements, the heading "Original Work" should not be used (and vice-versa).
I think this system would be intuitive, easy to understand and straightforward to put into practice. It's also consistent with modern bibliographical practice (e.g. putting original versions before arrangements, and complete works before extracts), and in most instances would not require major changes to the existing pages.
What do you think? Polite criticism only please
