Thanks Giovanni,

The documentation is however incomplete, the info node "(org) Column
groups" does not says that the `/' in the first field has the effect of
excluding the row from export. Actually when you read this info node,
what you (or better said I) understand is that the `/' indicates that
this special row is used to specify column grouping.

Therefore I propose the attached patch to documentation.

   Vincent.

PS-1: Sorry if sometimes I disturbe this group with naive questions.
PS-2: This is a resend, it seems that the previous message was not
dispatched due to this that I made a too big attachement (tarzipped 
complete manual old and new version in addition to patch).