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--- en:mei-friend-compendium [2026/05/03 15:17] – egorpoly
+++ en:mei-friend-compendium [2026/05/12 00:57] (aktuell) – egorpoly
@@ Zeile 586: / Zeile 586: @@
   * does the ''facs'' value point to the correct zone id?
   * does each measure point to exactly the intended measure zone?
+==== Duration encoding: dur vs. dur.ppq ====
+Please encode written musical duration with ''dur'' and, where needed, ''dots''.
+''dur'' records the notated value, for example ''dur="4"'' for a quarter note or ''dur="8"'' for an eighth note. ''dur.ppq'' records a calculated playback/timing value in pulses per quarter note. It is not the editorial duration and does not represent the visual notation directly.
+Local directive:
+  * use ''dur'' and ''dots'' as the authoritative duration encoding
+  * do not add ''dur.ppq'' to notes, rests, chords, or spaces
+  * do not add ''ppq'' to ''staffDef'' or ''scoreDef''
+  * remove existing ''dur.ppq'' and ''ppq'' values from imported files during cleanup
+Reason:
+  * the edition is based on the facsimile and should preserve written notation, not generated timing data
+  * ''dur.ppq'' is usually import or playback residue and can disagree with the written ''dur''/''dots''
+  * rhythmic proofreading should check whether the written durations fill the measure
+Minimal checklist:
+  * does every timed event have a clear written ''dur'' where required?
+  * are dotted values encoded with ''dots''?
+  * have ''dur.ppq'' and ''ppq'' been removed?
+==== Cross-staff notation ====
+For cross-staff chords encode it as one logical ''<chord>'' in a single ''<layer>'', and place the low (or high) note on the other staff with ''staff="5"'' (use the number of corresponding staff). The lower (or higher) staff's time is then filled with ''<space/>'' so that the rhythmic alignment remains complete.
+The MEI guidelines explicitly give this as an alternative for cross-staff chords. Some software handles this method better than separate cross-staff notes connected only by ''stem.with''.
+Example:
+<code xml>
+<staff xml:id="j138ax0t" n="4">
+  <layer xml:id="lie03m1" n="1">
+    <chord xml:id="n1v09lce" dur="8" stem.dir="up">
+      <note xml:id="m11lbwz8" oct="4" pname="f"/>
+      <note xml:id="ooukl9j" oct="4" pname="d"/>
+      <note xml:id="dgfh734" oct="3" pname="b" staff="5"/>
+    </chord>
+    ...
+  </layer>
+</staff>
+<staff xml:id="k10lc1io" n="5">
+  <layer n="2">
+    <space dur="8"/>
+    <note xml:id="dfj82467" dur="4" oct="3" pname="g" stem.dir="up"/>
+    <note xml:id="dfj82d467" dur="4" oct="3" pname="a" stem.dir="up"/>
+  </layer>
+</staff>
+</code>
+For mei-friend / Verovio-style workflows, this second version is often the more robust semantic encoding because it represents one chord rather than two separate events that merely share a stem.
+Local recommendation:
+  * use a single ''<chord>'' with note-level ''staff'' when the source clearly shows one chord split across staves
+  * fill the destination staff's elapsed time with ''<space/>'' when that staff has no independent sounding event at that moment
+  * keep the written duration on the ''<chord>'' with ''dur''