Add documentation for the new age operators.

doc/ChangeLog

@@ -3,6 +3,12 @@
 	* org.texi (Structure editing, Plain lists): Document indentation
 	cycling in empty entries with TAB.
 
+2009-11-01  James TD Smith  <ahktenzero@mohorovi.cc>
+
+	* org.texi (Column attributes): Add the new age summary operators.
+	Also, mention the fact you can only use one summary operator per
+	property.
+
 2009-10-31  Carsten Dominik  <carsten.dominik@gmail.com>
 
 	* orgcard.tex: Document the new archiving keys.

doc/org.texi

@@ -4586,35 +4586,42 @@ optional.  The individual parts have the following meaning:
 
 @example
 @var{width}           @r{An integer specifying the width of the column in characters.}
-                @r{If omitted, the width will be determined automatically.}
+		@r{If omitted, the width will be determined automatically.}
 @var{property}        @r{The property that should be edited in this column.}
 (title)         @r{The header text for the column. If omitted, the}
-                @r{property name is used.}
+		@r{property name is used.}
 @{@var{summary-type}@}  @r{The summary type.  If specified, the column values for}
-                @r{parent nodes are computed from the children.}
-                @r{Supported summary types are:}
-                @{+@}       @r{Sum numbers in this column.}
-                @{+;%.1f@}  @r{Like @samp{+}, but format result with @samp{%.1f}.}
-                @{$@}       @r{Currency, short for @samp{+;%.2f}.}
-                @{:@}       @r{Sum times, HH:MM:SS, plain numbers are hours.}
-                @{X@}       @r{Checkbox status, @samp{[X]} if all children are @samp{[X]}.}
-                @{X/@}      @r{Checkbox status, @samp{[n/m]}.}
-                @{X%@}      @r{Checkbox status, @samp{[n%]}.}
-                @{min@}     @r{Smallest number in column.}
-                @{max@}     @r{Largest number.}
-                @{mean@}    @r{Arithmetic mean of numbers.}
-                @{:min@}    @r{Smallest time value in column.}
-                @{:max@}    @r{Largest time value.}
-                @{:mean@}   @r{Arithmetic mean of time values.}
+		@r{parent nodes are computed from the children.}
+		@r{Supported summary types are:}
+		@{+@}       @r{Sum numbers in this column.}
+		@{+;%.1f@}  @r{Like @samp{+}, but format result with @samp{%.1f}.}
+		@{$@}       @r{Currency, short for @samp{+;%.2f}.}
+		@{:@}       @r{Sum times, HH:MM:SS, plain numbers are hours.}
+		@{X@}       @r{Checkbox status, @samp{[X]} if all children are @samp{[X]}.}
+		@{X/@}      @r{Checkbox status, @samp{[n/m]}.}
+		@{X%@}      @r{Checkbox status, @samp{[n%]}.}
+		@{min@}     @r{Smallest number in column.}
+		@{max@}     @r{Largest number.}
+		@{mean@}    @r{Arithmetic mean of numbers.}
+		@{:min@}    @r{Smallest time value in column.}
+		@{:max@}    @r{Largest time value.}
+		@{:mean@}   @r{Arithmetic mean of time values.}
+		@{@@min@}   @r{Minimum age (in days/hours/mins/seconds).}
+		@{@@max@}   @r{Maximum age (in days/hours/mins/seconds).}
+		@{@@mean@}  @r{Arithmetic mean of ages (in days/hours/mins/seconds).}
 @end example
 
 @noindent
+Be aware that you can only have use one summary type for any property you
+include. Subsequent columns referencing the same property will al display the
+same summary information.
+
 Here is an example for a complete columns definition, along with allowed
 values.
 
 @example
 :COLUMNS:  %25ITEM %9Approved(Approved?)@{X@} %Owner %11Status \@footnote{Please note that the COLUMNS definition must be on a single line---it is wrapped here only because of formatting constraints.}
-                   %10Time_Estimate@{:@} %CLOCKSUM
+		   %10Time_Estimate@{:@} %CLOCKSUM
 :Owner_ALL:    Tammy Mark Karl Lisa Don
 :Status_ALL:   "In progress" "Not started yet" "Finished" ""
 :Approved_ALL: "[ ]" "[X]"