some precision on coords for groups

1 files changed, 8 insertions, 4 deletions

diff --git a/doc/refman.tex b/doc/refman.tex
index 6c14e42..95f514d 100644
--- a/doc/refman.tex
+++ b/doc/refman.tex
@@ -964,15 +964,18 @@ coordinate system maps exactly on the system of its group. The commands
 this relationship to the effect of translating, enlarging, shrinking or
 rotating the item. It must be emphasized that those commands act on the
 relation between two coordinate spaces, \emph{not} on the item geometry itself.
-If the goal is to change the item geometry, the command \cmdref{coords} may be
-more appropriate (but see below the command \cmdref{tapply}).
+If the goal is to change the item (except for groups, see next paragraph) geometry,
+the command \cmdref{coords} may be more appropriate (but see below the command
+\cmdref{tapply}).
 
 As it should be clear, groups are like any other items, they are defined in
 their own coordinate space and are assembled with their parents by transformations.
 This is a very powerful tool to manage the geometry of clusters of items.
 One must not refrain from using groups only to assign them a transformation
 task such as panning a whole set of items or scaling a set while another is
-kept in place in another group.
+kept in place in another group. For the developper convenience, the \cmdref{coords}
+method on a group change its transformation. It defines the absolute translation
+applied to the group.
 
 Another very interesting use of a group as a transformation tool is to manage a window
 coordinate space where the origin is not in the top left corner and where the Y axis goes
@@ -1838,7 +1841,8 @@ false.
 {\tt\large \$zinc->{\bf coords}(tagOrId, ?add/remove?, ?contour?, ?index?, ?coordList?);}
 
 \begin{blockindent}
-  Query or changes the coordinates of the item described by {\tt tagOrId}. If {\tt
+  Query or changes the coordinates of the item described by {\tt tagOrId}. If the
+  item is a group, query or set the translation applied to the group. If {\tt
   tagOrId} describes more than one item, the first in display list order is used. The
   optional {\tt contour} gives the contour, if available, that should be operated. The
   default contour is 0. The optional {\tt index} gives the vertex index that should be