[O] [PATCH] document parent property update in column view

[Hendrik Tews]

---
 doc/org.texi | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/doc/org.texi b/doc/org.texi
index 142fa9627..11c6a0f39 100644
--- a/doc/org.texi
+++ b/doc/org.texi
@@ -5263,7 +5263,8 @@ keeping track of your music CDs, where properties could 
be things such as the
 album, artist, date of release, number of tracks, and so on.
 
 Properties can be conveniently edited and viewed in column view
-(@pxref{Column view}).
+(@pxref{Column view}). For certain applications Org mode can compute and
+update certain properties, @pxref{Column attributes}.
 
 @menu
 * Property syntax::             How properties are spelled out
@@ -5641,6 +5642,15 @@ optional.  The individual parts have the following 
meaning:
                 @address@hidden    @r{Add @samp{low-high} estimates.}
 @end example
 
+When the column definition contains a summary type, Org mode computes the
+value for parent nodes (i.e., those nodes that contain children nodes). If
+the property is present in the parent node, its value is ignored during the
+computation, but Org mode will update the parent property with the computed
+value afterwards. The computation happens when column view is started and
+when values are updated using the column view interface, @pxref{Using column
+view}. A missing value in a leaf node is treated as zero and can cause
+unexpected results, for instance for the @code{mean} summary type.
+
 The @code{est+} summary type requires further explanation.  It is used for
 combining estimates, expressed as @samp{low-high} ranges or plain numbers.
 For example, instead of estimating a particular task will take 5 days, you
-- 
2.11.0