diff --git a/home/bin/deboco b/home/bin/deboco
index dd4988c..710f03e 100755
--- a/home/bin/deboco
+++ b/home/bin/deboco
@@ -476,7 +476,7 @@ common_update_machine()
 	local debops_controller_path="$1"
 	local target_host_fqdn="$2"  # eg alambix-108.ipr.univ-rennes.fr
 	local only_role="$3"  # eg "role::xymon_server" or "role::rsyslog" or "" if all roles need to be applied
-	local machine_group="$4"  # eg 'site' or 'service/apache2'
+	local playbook="$4"  # eg 'site' or 'service/apache2'
 	debops_controller_path=$(realpath $debops_controller_path)
 	log 'info' "updating $target_host_fqdn using debobs controller $debops_controller_path"
 
@@ -536,24 +536,21 @@ deboco__update_machine()
 	local debops_controller_path="$1"
 	local target_host_fqdn="$2"  # eg alambix-108.ipr.univ-rennes.fr
 	local only_role=""
-	local machine_group="site"
-	common_update_machine "$debops_controller_path" "$target_host_fqdn" "$only_role" "$machine_group"
+	local playbook="site"
+	common_update_machine "$debops_controller_path" "$target_host_fqdn" "$only_role" "$playbook"
 }
 
 deboco__update_machine_partially()
 {
 	local debops_controller_path="$1"
 	local target_host_fqdn="$2"  # eg alambix-108.ipr.univ-rennes.fr
-	local only_role="$3"  # eg "role::xymon_server" or "role::rsyslog" or "" if all roles need to be applied
-	local service="$4"  # eg "nginx" "apache2"
-	local machine_group=''
-	if [ "$service" = "" ]
+	local only_role="$3"  # eg "role::xymon", "role::xymon_server" or "role::rsyslog" or "" if all roles need to be applied
+	local playbook="$4"  # eg "site", "ipr", "service/nginx" "service/apache2"
+	if [ "$playbook" = "" ]
 	then
-		machine_group='site'
-	else
-		machine_group="service/$service"
+		playbook='site'
 	fi
-	common_update_machine "$debops_controller_path" "$target_host_fqdn" "$only_role" "$machine_group"
+	common_update_machine "$debops_controller_path" "$target_host_fqdn" "$only_role" "$playbook"
 }
 
 deboco_print_usage()
@@ -581,8 +578,8 @@ deboco_print_usage()
 	echo "     update_machine <debobs-controller-path> <machine-fqdn>"
 	echo "        updates the machine <machine-fqdn> using the debops controller in <debobs-controller-path>"
 	echo 
-	echo "     update_machine_partially <debobs-controller-path> <machine-fqdn> <role> <service>"
-	echo "        updates the role <role> on machine <machine-fqdn> belonging to service <service> using the debops controller in <debobs-controller-path>"
+	echo "     update_machine_partially <debobs-controller-path> <machine-fqdn> <role> <playbook>"
+	echo "        updates the role <role> on machine <machine-fqdn> of playbook <playbook> using the debops controller in <debobs-controller-path>"
 	echo 
 	echo "     configure_machine <debobs-controller-path> <machine-fqdn>"
 	echo "        configures the machine <machine-fqdn> using the debops controller in <debobs-controller-path>". Equivalent to a init_machine followed by update_machine
@@ -591,7 +588,11 @@ deboco_print_usage()
 	echo "     deboco --python-path /usr/bin/python3.10 init ~/work/debops/controllers/alambix"
 	echo 
 	echo "example to update xymon server's configuration (here it's much faster to specify the service apache than an unspecified service: 16s instead of 3m 33s):"
-	echo "     deboco update_machine_partially ~/debops/controllers/alambix monitoring.ipr.univ-rennes.fr role::xymon_server apache"
+	echo "     deboco update_machine_partially ~/debops/controllers/alambix monitoring.ipr.univ-rennes.fr role::xymon_server service/apache"
+	echo 
+	echo "example to update xymon client's configuration on alambix50 (the playbook that uses the role xymon (ie xymon client)) is currently ipr.post.debops):"
+	echo "     deboco update_machine_partially ~/debops/controllers/alambix alambix50.ipr.univ-rennes.fr 'role::xymon' 'ipr.post.debops"
+	
 }
 
 deboco()