diff --git a/inc_pluginfunctions b/inc_pluginfunctions
index 39f583841f7afcb7545f719b5f9992743a451d73..9771ef5dd3705f711c6db6f0f72987c6c8928e12 100644
--- a/inc_pluginfunctions
+++ b/inc_pluginfunctions
@@ -393,9 +393,12 @@ function ph._perfinit(){
 function ph._getperflabel(){
   echo "$1" | tr [:upper:] [:lower:] | sed "s#[^a-z0-9\-]##g"
 }
+
 # get speed of change of a counter value
-# param1: string    variable name
-# param2: integer   value
+# param  string    variable name
+# param  integer   value
+# param  string    unit to calculate a speed value per min or per sec; one of s|sec or m|min; default: "s"
+# param  string    optional: flag to return a float value
 function ph.perfdeltaspeed(){
         local varName=$1
         local value=$2
@@ -453,6 +456,13 @@ function ph.perfdeltaspeed(){
 #
 # example
 # ph.perfadd  
+#
+# param  string     label
+# param  int|float  your value
+# param  integer    optional: warning level
+# param  integer    optional: critical level
+# param  integer    optional: min graph value
+# param  integer    optional: max graph value
 function ph.perfadd(){
   if [ -z "$ph_perfdatafile" ]; then
     ph._perfinit