diff --git a/exec_eval_preconditions.lua b/exec_eval_preconditions.lua
index 3b7bd02..a051772 100644
--- a/exec_eval_preconditions.lua
+++ b/exec_eval_preconditions.lua
@@ -1,13 +1,57 @@
 -- This file contains what is necessary to execute/evaluate a precondition.
 
 -- some internal ones...
-yl_speak_up.precondition_check_variable = {
---	"- please select -", -- this is automaticly added to the var list
-	"(internal) hour of ingame day", -- 2
-	"(internal) player's health points", -- 3
+yl_speak_up.custom_server_functions = {}
+
+
+-- When you change an existing texts NPC that make use of that precondition will no
+-- longer be able to recognize it. You have to reconfigure all those NPC!
+-- Adding new texts is no problem.
+yl_speak_up.custom_server_functions.precondition_descriptions = {
+	"(internal) hour of ingame day",
+	"(internal) player's health points",
+	"(internal) player has priv:",
 }
 
 
+-- please return a useful value depending on the function;
+-- parameter:
+-- 	player		the player object
+-- 	desc		entry from yl_speak_up.custom_server_functions.precondition_descriptions
+-- 	precondition	the data of the precondition for additional information;
+-- 			precondition.p_var_cmp_value contains a user-specified value against which
+-- 			the return value of this function is checked. This depends on
+-- 			precondition.p_operator. Depending on the operator, precondition.p_var_cmp_value
+-- 			may also be used as a parameter to this function.
+-- 			Just make sure to tell your users what return values they shall expect and which
+-- 			operators make sense!
+yl_speak_up.custom_server_functions.precondition_eval = function(player, descr, precondition)
+
+	if(descr == "(internal) hour of ingame day") then
+		-- timeofday is between 0..1; translate to 24 hours
+		return math.floor((minetest.get_timeofday() * 24)+0.5)
+
+	elseif(descr == "(internal) player's health points") then
+		return player:get_hp()
+
+	elseif(descr == "(internal) player has priv:") then
+		-- the name of the priv is derived from the parameter
+		if(minetest.check_player_privs(player,
+				minetest.string_to_privs(tostring(precondition.p_var_cmp_value)))) then
+			-- TODO: change to true/false when new operator is available
+			return tostring(precondition.p_var_cmp_value)
+		else
+			return "false"
+		end
+
+	-- if this custom server function does not exist: return false
+	else
+		return false
+	end
+end
+
+
+
 -- this is called directly in yl_speak_up.get_fs_talkdialog
 -- it returns a list of options whose preconditions are fulfilled
 -- allow_recursion may be false - we need to avoid infinite loops
@@ -100,13 +144,13 @@ yl_speak_up.eval_precondition = function(player, n_id, p, other_options_true_or_
 		if(not(p.p_variable) or p.p_variable == "") then
 			-- broken precondition
 			return false
-		-- "(internal) hour of ingame day", -- 2
-		elseif(p.p_variable == yl_speak_up.precondition_check_variable[2]) then
-			-- timeofday is between 0..1; translate to 24 hours
-			var_val = math.floor((minetest.get_timeofday() * 24)+0.5)
-		-- "(internal) player's health points", -- 3
-		elseif(p.p_variable == yl_speak_up.precondition_check_variable[3]) then
-			var_val = player:get_hp()
+		-- internal custom server functions for preconditions
+		elseif(table.indexof(yl_speak_up.custom_server_functions.precondition_descriptions,
+		                     p.p_variable) > -1) then
+			-- evaluate it
+			var_val = yl_speak_up.custom_server_functions.precondition_eval(
+					player, p.p_variable, p)
+print("VAR_VAL is: "..tostring(var_val)) -- TODO
 		else
 			local pname = player:get_player_name()
 			local owner = yl_speak_up.npc_owner[ n_id ]
diff --git a/fs_edit_general.lua b/fs_edit_general.lua
index c51e03c..d3e62d6 100644
--- a/fs_edit_general.lua
+++ b/fs_edit_general.lua
@@ -284,7 +284,18 @@ yl_speak_up.save_element_p_or_a_or_e = function(
 		v[ id_prefix.."value" ] = "expression"
 		v[ id_prefix.."operator" ] = values_operator[ data.operator ]
 		v[ id_prefix.."var_cmp_value" ] = (data.var_cmp_value or "")
-		v[ id_prefix.."variable" ] = yl_speak_up.add_pname_to_var(data.variable_name, pname)
+		-- if it is a custom server function,then do not preifx it with $ playername
+		if(id_prefix == "p_") then
+			local idx = table.indexof(yl_speak_up.custom_server_functions.precondition_descriptions,
+			                          data.variable_name)
+			if(idx > -1) then
+				v[ id_prefix.."variable" ] = data.variable_name
+			else
+				v[ id_prefix.."variable" ] = yl_speak_up.add_pname_to_var(data.variable_name, pname)
+			end
+		else
+			v[ id_prefix.."variable" ] = yl_speak_up.add_pname_to_var(data.variable_name, pname)
+		end
 
 	-- "a block somewhere", -- 3
 	elseif(what_type == "block" and id_prefix ~= "a_") then
diff --git a/fs_edit_preconditions.lua b/fs_edit_preconditions.lua
index 5fdf11a..eb0d48a 100644
--- a/fs_edit_preconditions.lua
+++ b/fs_edit_preconditions.lua
@@ -152,8 +152,8 @@ local values_operator = {"", "==", "~=", ">=", ">", "<=", "<", "not", "is_set",
 -- get the list of variables the player has read access to
 yl_speak_up.get_sorted_player_var_list_read_access = function(pname)
 	local var_list = {}
-	-- copy the values from check_variable
-	for i, v in ipairs(yl_speak_up.precondition_check_variable) do
+	-- copy the values that are server-specific
+	for i, v in ipairs(yl_speak_up.custom_server_functions.precondition_descriptions) do
 		table.insert(var_list, v)
 	end
 	-- get the list of variables the player can read