Issue 4579: NR Changing Defaults: Explain sticky contexts accurately

diff --git a/Documentation/notation/changing-defaults.itely b/Documentation/notation/changing-defaults.itely
index 246504aeb91ddb568c92d8814003c844a2354e9d..efcf8549b3d35ac6e152a64874eed1cabfbf00f7 100644 (file)
--- a/Documentation/notation/changing-defaults.itely
+++ b/Documentation/notation/changing-defaults.itely
@@ -536,14 +536,19 @@ have to be referenced, for example, when changing staves with
 @code{\lyricsto} commands, or when adding further musical events to
 an earlier context.
 
-There is an exception to this general rule: just one of the
-@code{Voice} contexts in a @code{Staff} context or in a
-@code{<<@dots{}>>} construct will always persist to the end of the
-enclosing @code{Staff} context or @code{<<@dots{}>>} construct, even
-though there may be periods when it has nothing to do.  The context
-to persist in this way will be the first one encountered in the
-first enclosed @code{@{@dots{}@}} construct, ignoring any in enclosed
-@code{<<@dots{}>>} constructs.
+There is an exception to this general rule: inside of an
+@code{@{@dots{}@}} construct (sequential music), the construct's
+notion of the ``current context'' will descend whenever an element
+of the sequence ends in a subcontext of the previous current
+context.  This avoids spurious creation of implicit contexts in a
+number of situations but means that the first context descended
+into will be kept alive until the end of the expression.
+
+In contrast, the contexts of a @code{<<@dots{}>>} construct's
+(simultaneous music) expression are not carried forth, so
+enclosing a context creating command in an extra pair of
+@code{<<@dots{}>>} will keep the context from persisting through
+all of the enclosing @code{@{@dots{}@}} sequence.
 
 Any context can be kept alive by ensuring it has something to do at
 every musical moment.  @code{Staff} contexts are kept alive by