diff --git a/common_func.php b/common_func.php
index 5c5a463..d2cb088 100644
--- a/common_func.php
+++ b/common_func.php
@@ -1,8 +1,8 @@
 <?php
 
 function explode_list(string $str) : array {
-    if (trim($str) !== "") {
-        return explode(",", str_replace(" ", "", $str));
+    if (($str = trim($str, " \n\r\t\v\0,")) !== "") {
+        return array_map(fn($a) => trim($a), explode(",", str_replace(" ", "", $str)));
     } else {
         return [];
     }
diff --git a/interface.php b/interface.php
index aa1f469..b5daeab 100644
--- a/interface.php
+++ b/interface.php
@@ -47,7 +47,7 @@ $success = false;
 $user = null;
 $nickname = "";
 $privilege = PRIVILEGE_NONE;
-$is_quizmaster = false;
+
 // --------
 
 // create request handler
@@ -94,7 +94,6 @@ if ((session_status() != PHP_SESSION_ACTIVE) || (!isset($_SESSION["nickname"]))
 $user = $userMgr->getUser($_SESSION["nickname"]);
 $nickname = $user->getNickname();
 $privilege = $user->getPrivilege();
-$is_quizmaster = $privilege === PRIVILEGE_QUIZMASTER;
 $groupMgr = new GroupMgr();
 $gameMgr = new GameMgr();
 $testMgr = new TestMgr();
@@ -320,7 +319,7 @@ if ($privilege === PRIVILEGE_PLAYER) {
 
 /* --------------- CREATOR LEVEL ACTIONS ---------------- */
 
-$requester_nickname = $is_quizmaster ? "*" : $nickname; // "*" means every game
+$requester_nickname = $user->hasQuizmasterPrivilege() ? "*" : $nickname; // "*" means every game
 
 function create_update_game(ReqHandler &$rh, array $params): array
 {
@@ -479,7 +478,7 @@ function export_game_file_csv(ReqHandler &$rh, array $params): string
     return "";
 }
 
-function get_player_results_by_gameid(ReqHandler &$rh, array $params): array
+function get_results_by_gameid(ReqHandler &$rh, array $params): array
 {
     global $gameMgr;
     global $testMgr;
@@ -524,7 +523,7 @@ $rh->add("get_all_game_headers", [], PRIVILEGE_CREATOR, "get_all_game_headers",
 $rh->add("get_challenges", [], PRIVILEGE_CREATOR, "get_challenges", RESP_PLAIN, "Get game challenges.");
 $rh->add("delete_games", ["ids"], PRIVILEGE_CREATOR, "delete_games", RESP_PLAIN, "Delete games.");
 $rh->add("export_game_file_csv", ["gameid"], PRIVILEGE_CREATOR, "export_game_file_csv", RESP_NONE, "Export game CSV file.");
-$rh->add("get_results_by_gameid", ["gameid"], PRIVILEGE_CREATOR, "get_player_results_by_gameid", RESP_JSON, "Get game results.");
+$rh->add("get_results_by_gameid", ["gameid"], PRIVILEGE_CREATOR, "get_results_by_gameid", RESP_JSON, "Get game results.");
 $rh->add("generate_detailed_stats", ["gameid", "testids"], PRIVILEGE_CREATOR, "generate_detailed_game_stats", RESP_JSON, "Generate detailed game stats.");
 $rh->add("delete_tests", ["ids"], PRIVILEGE_CREATOR, "delete_tests", RESP_PLAIN, "Delete tests.");
 
@@ -590,7 +589,7 @@ function delete_groups(ReqHandler &$rh, array $params): string
     return "OK";
 }
 
-function get_all_player_groups(ReqHandler &$rh, array $params): array
+function get_all_groups(ReqHandler &$rh, array $params): array
 {
     global $groupMgr;
     $groups = $groupMgr->getAllGroups();
@@ -601,7 +600,7 @@ function get_all_player_groups(ReqHandler &$rh, array $params): array
     return $a;
 }
 
-function search_player_groups(ReqHandler &$rh, array $params): array
+function search_groups(ReqHandler &$rh, array $params): array
 {
     global $groupMgr;
     $groups = $groupMgr->searchGroups($params["needle"]);
@@ -660,7 +659,7 @@ function delete_users(ReqHandler &$rh, array $params): string
     return "OK";
 }
 
-function get_all_game_users(ReqHandler &$rh, array $params): array
+function get_all_users(ReqHandler &$rh, array $params): array
 {
     global $userMgr;
     $user_data_filtered = [];
@@ -718,13 +717,13 @@ function import_users_from_csv(ReqHandler &$rh, array $params): string
 $rh->add("create_group", ["groupname", "description"], PRIVILEGE_QUIZMASTER, "create_update_group", RESP_PLAIN, "Create group.");
 $rh->add("update_group", ["groupname", "description", "owner", "editors", "id"], PRIVILEGE_QUIZMASTER, "create_update_group", RESP_PLAIN, "Update group.");
 $rh->add("delete_groups", ["ids"], PRIVILEGE_QUIZMASTER, "delete_groups", RESP_PLAIN, "Delete group.");
-$rh->add("get_all_groups", [], PRIVILEGE_QUIZMASTER, "get_all_player_groups", RESP_JSON, "Get all player groups.");
-$rh->add("search_groups", ["needle"], PRIVILEGE_QUIZMASTER, "search_player_groups", RESP_JSON, "Serach and fetch player groups.");
+$rh->add("get_all_groups", [], PRIVILEGE_QUIZMASTER, "get_all_groups", RESP_JSON, "Get all player groups.");
+$rh->add("search_groups", ["needle"], PRIVILEGE_QUIZMASTER, "search_groups", RESP_JSON, "Serach and fetch player groups.");
 $rh->add("change_group_members", ["groupid", "add", "remove"], PRIVILEGE_QUIZMASTER,"change_group_members", RESP_PLAIN, "Change group members.");
 
 $rh->add(["create_user", "update_user"], ["nickname", "password", "realname", "privilege"], PRIVILEGE_QUIZMASTER, "create_update_user", RESP_PLAIN, "Create or update user.");
 $rh->add("delete_users", ["users"], PRIVILEGE_QUIZMASTER, "delete_users", RESP_PLAIN, "Delete users.");
-$rh->add("get_all_users", [], PRIVILEGE_QUIZMASTER, "get_all_game_users", RESP_JSON, "Get all users.");
+$rh->add("get_all_users", [], PRIVILEGE_QUIZMASTER, "get_all_users", RESP_JSON, "Get all users.");
 $rh->add("get_user_groups", ["nickname"], PRIVILEGE_QUIZMASTER, "get_user_groups", RESP_JSON, "Get user's groups.");
 $rh->add("get_game_groups", ["gameid"], PRIVILEGE_QUIZMASTER, "get_game_groups", RESP_JSON, "Get game's groups.");
 $rh->add("import_users_from_csv", [], PRIVILEGE_QUIZMASTER, "import_users_from_csv", RESP_JSON, "Get all users.");