I've searched a few moment and found an answer to my problem...
I'd like to understand why my pdf dashbaords expors show "$field1$" instead of "PE0101" (serveur name) in graph title.
I found this, here on docs.splunk.com/Documentation/ :
that it is question of xml format, simple or advanced and variables are not translated into pdf export with advances xml dashboards.
Any way i could satisfy myslef but not really.
Please see in 1st screenshot that everything is OK in the dashboard called "Backbone PING - Etats des Interfaces" using IHM or pdf export.
Please notice in 2nd screenshot that everything is NOT OK in the dashboard called "Backbone PING - Graphes Equipement" using IHM is OK but using pdf export is NOT OK, variables are not set.
I use in both dashboards this kind of personnale xml code
I think beeing in advanced xml mode with both dashboards so why the 1st exports variables in pdf and not the 2nd..... ?