[MEI-L] symbol/symbolDef

[Roland, Perry (pdr4h)]

Hi, Thomas,

The <symbolDef> element is intended to allow the inclusion of arbitrary symbols/signs.  Using <symbolDef>, one can say how a symbol should be drawn in terms of its graphic components; that is, text, curves, and lines. After defining the symbol's coordinate space (using @ulx, @uly, @lrx, and @lry), the <anchoredText>, <curve>, and <line> elements (with appropriate x, y, x2, and y2 attributes) can be used to construct the symbol.

The <symbol> element can then be used to make reference to this user-defined sign.

For example, one could define a new sign within <scoreDef> --

<scoreDef>
  <symbolTable>
    <symbolDef xml:id="mySign" ulx="0" uly="0" lrx="20" lry="20">
      <line x="10" y="0" x2="10" y2="10"/>
      <line x="10" y="10" x2="20" y2="10"/>
      <line x="20" y="10" x2="20" y2="20"/>
    </symbolDef>
  </symbolTable>
</scoreDef>

then later in the document data invoke this symbol --

<measure>
  <staff n="1">
    <layer>
      <note xml:id="n1" .../>
        ...
    </layer>
  </staff>
  <symbol ref="mySign"/>
</measure>

<symbolDef> may contain references to other <symbol> elements.  If a line of a certain length and style is a common component, it can be defined once and re-used.

The symbol can be placed relative to elements in the notation (using some combination of ho, vo , and to attributes) --

<symbol startid="n1" ho="5"/>

(This example indicates the symbol is placed at the same vertical position as, but 5 half-step units above, n1.)

<symbol> and <symbolDef> cannot be used to point to a feature in a facsimile image because they have no @facs attribute.  This was done purposefully in order to encourage the use of elements of the notation; that is, <note>, <chord>, <staff>, etc., for this purpose.

<annot> can be used to record commentary on symbols just as it can with other elements of notation.  It's technically possible make a <symbolDef> element a target (using @plist), but I think <symbol> is the proper target.  In other words, <symbol> is a generic placeholder for an "unknown" notational sign.  <symbolDef> is "just" the instructions for drawing it.

Does that help?

--
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-bounces+pdr4h=virginia.edu at lists.uni-paderborn.de [mei-l-bounces+pdr4h=virginia.edu at lists.uni-paderborn.de] on behalf of TW [zupftom at googlemail.com]
Sent: Friday, March 16, 2012 3:54 AM
To: Music Encoding Initiative
Subject: [MEI-L] symbol/symbolDef

I'd like to ask for your opinion on some aspects of the usersymbols
module as I'm in charge of its guidelines.

I'm not particularly clear how the relationship between <symbolDef>
and <symbol> is meant to work.  <symbolDef> mustn't be an empty
element, so I might want to put a <symbol> element inside that might
have a @facs attribute to point to a graphical example representation
of the symbol.  But this <symbol> element is required to have a @ref
attribute which must be "a reference to a previously-declared
user-defined symbol".  The dog seems to chase its tail, right?

One use case I see for <symbol> is if we have a scribe who uses some
unusual symbols that might possibly not be fully understood.  Then I
might want to give some textual information about what meaning my
research has suggested or what use pattern can be recognized.  Would I
do this with an <annot>, pointing to <symbolDef> by means of @plist?

Thanks for your help!
Thomas Weber

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