[MEI-L] First efforts to bring modal notation to MEI

[Janek Spaderna]

Hello everyone,

as a project for university I am looking into the challenges of bringing
support for modal notation to MEI. I am quite new to both modal notation and
MEI so please don’t hesitate to let me know in case I mix things up, miss
something or end up writing straight up wrong stuff.

Instead of directly thinking in terms of a (potential) concrete encoding I
would like to discuss the elements and concepts of modal notation first.
Below you can find the thoughts I had so for in this regard.

In my opinion thinking this through beforehand can help because we can get a
feeling on which level an encoding should work: rather purely visual or should
it include/require analysis of some (which?) sort.

The only prior discussion about this I could find is a thread initiated by
Joshua Stutter about two years ago [1]. (Did I miss something?) It touches on
some of the concepts which exist in modal notation but have disappeared in
mensural music but is mostly concerned with finding a concrete encoding for
some piece of music.


# Visual elements of modal notation

The distinctive visual elements are only very few: lines, clefs, notes, tractus
and lyrics.

Regarding notes there are some special cases:

 a) notes can be grouped into ligatures
 b) a note can have a plica attached
 c) notes can be followed by currentes, making it a coniunctura
 d) the last note in a ligature can also be coniunctura

Cases a) and b) also occur in mensural notation; about c)/d) I am not sure, at
least I think I do not have seen a way to encode it in MEI?

Also for c) there is a difference in musical meaning wether there is a note
followed by up to three lozenges or if there are more than three. The former
corresponds to a ternaria whereas only the latter is truly a coniunctura.

Tractus serve multiple purposes:

 1. It groups notes into ordines.
 2. It indicates syllable changes.
 3. It indicates alignment of different voices in organum passages.


# Concepts of modal notation

## Tempora, perfectiones, ordines

The rhythmic feeling is based on perfectiones which consist of three tempora.
If not changed by context a brevis has a length of one tempus, a longa of two.
Only having seen a few transcription I still got the feeling that it is quite
common to number the perfectiones.

Notes are grouped by tractus into ordines. The duration of an ordo is not fix
and can encompass one or more perfectiones. The tractus which ends an ordo is
usually transcribed as a rest with a context dependet duration.


## Discantus/organum purum

On one side there is the discantus, on the other the organum purum. In between
the two lives the copula.

In discantus passages each voice follows a mode which can be recognized by a
specific pattern of ligatures. The mode then tells which notes in the ligatures
are longae and which are breves. Additional notes---be it from overlong
ligatures not fitting the patterns or coniuncturae---live outside the
longa/breve classification.

This concept does not apply to organum purum. As I understand it the most
important bit here is finding a way to encode the visual alignment of the
voices. Karen Desmond writes in one of her responses to the aforementioned
thread on the mailing list [2]

> Ideally you would probably want to number the perfections and then you would
> simply tag your tenor notes as occurring within a certain perfection.

Whilst she notes other problems with this idea I am wondering if this would
even be feasible in organum purum passages as I thought we do not know which
notes are longae and which are breves. As I read it, Joshua shares my
sentiment [3]

> I'm against tagging in a particular perfection as that is implying that the
> music proceeds in a constant modal rhythm and has length, which may not be
> exactly correct.

The copula is used to connect discantus passages with organum purum passages.
During these connecting sections the duplum operates as in discantus sections
whereas the tenor holds notes as in organum purum passages.

Overall it can be said that a way to encode alignment is important in organum
purum and copula passages. In discantus passages however this is not necessary
as the modal rhythm used in all voices carries enough information; moreover the
visual alignment usually does not even correspond to the musical alignment.

-------------------------------


What are your thoughts so far? I am looking forward to your feedback!

Best
Janek


[1]: https://lists.uni-paderborn.de/pipermail/mei-l/2019/002268.html  Joshua Stutter’s initial message
[2]: https://lists.uni-paderborn.de/pipermail/mei-l/2019/002272.html  Karen Desmond in response to Joshua
[3]: https://lists.uni-paderborn.de/pipermail/mei-l/2019/002280.html  Joshua in response to Karen