[MEI-L] Mei Repeats

[Roland, Perry D. (pdr4h)]

Hi Tristano,

I thought this was covered in the Guidelines, but taking a closer look, I find that it isn't.  So, I'll try to explain.

There are multiple aspects of repeated sections that must be taken into account.  First, there are the signs found in the notation. Second, there is the question of how the signs should be interpreted in performance.  The first aspect is partially covered, as you already know, by the @left and @right attributes on <measure>.  The second is encoded using the <expansion> element.  <expansion> provides the means to encode the performance order of <section> and <ending> elements.  There could be multiple interpretations of the repeat structure, so <expansion> is repeatable.

Here's an encoding of the relevant portion of your first example:

<section>
  <expansion plist="A Ending1 A Ending1 A Ending2"/>
  <section xml:id="A">
    <measure n="1" left="rptstart"/>
    <!-- measures 2 - 8 -->
  </section>
  <ending n="1" xml:id="Ending1" label="1. 2.">
    <measure n="9" right="rptend"/>
  </ending>
  <ending n="2" xml:id="Ending2" label="3.>
    <measure n="10" right="end"/>
  </ending>
</section>

The repeat signs and the ending bar are encoded using @left and @right attributes.  <ending> elements are used to wrap the measures under the first and second ending brackets.  In order to be able to assign an ID to the repeated part of the music (measures 1 - 8), these measures are wrapped in a child <section> element.  It's the performance order of the children of this outer section that the <expansion> element's @plist attribute describes: section A, then Ending1, section A, then Ending1, section A, then Ending2.

The only other "wrinkle" is the labeling of the endings.  The @n attribute can be used to give a number or name to elements, such as the endings in this case.  But, since @n can only hold a single token, if you want a space in the name, it's better to use the @label attribute. (I'll leave the larger discussion of "name" vs. "label" for another time.)

Your second example doesn't introduce any new problems, so I leave it to you to work out its encoding.  If you run into difficulty, though, just let me know.

--
p.

__________________________
Perry Roland
Music Library
University of Virginia
P. O. Box 400175
Charlottesville, VA 22904
434-982-2702 (w)
pdr4h (at) virginia (dot) edu
________________________________
From: mei-l [mei-l-bounces at lists.uni-paderborn.de] on behalf of Tristano Tenaglia [tristano.tenaglia at mail.mcgill.ca]
Sent: Monday, June 15, 2015 3:28 PM
To: mei-l at lists.uni-paderborn.de
Subject: [MEI-L] Mei Repeats

Dear MEI Community,

I am wondering how repeats would be encoded in MEI. From the examples that I have seen so far, @left and @right attributes inside of measure elements can be given "rptstart" or "rptend" values and programs such as Verovio will interpret them accordingly. However let's say we have multiple endings with multiple bars or a multiple bar ending that needs to be repeated several times, then I am having trouble finding some examples.

I have included some sample photos to give you an idea of what I am looking for.

Would anyone be able to explain or send me some sample encoding of these cases?

Regards,
Tristano Tenaglia
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