+const static char* FEATURE_NESTED = "nested";
+const static char* FEATURE_WHEN_NESTED = "when_nested";
+const static char* FEATURE_WHEN_NESTED_ACCEPT = "accept";
+const static char* FEATURE_WHEN_NESTED_ABORT = "abort";
+const static char* FEATURE_DOC = WORKBENCH_DOC;
+const static char* FEATURE_MODAL = "modal";
+const static char* FEATURE_APPLY_CONTINUE = "apply_continue";
+const static char* FEATURE_AUTO_PREVIEW = "auto_preview";
+// NODE_VALIDATOR properties
+const static char* _PARAMETERS = "parameters";
+
+// Widget (attribute) properties
+const static char* ATTR_TOOLTIP = FEATURE_TOOLTIP;
+const static char* ATTR_ICON = FEATURE_ICON;
+const static char* ATTR_LABEL = "label";
+const static char* ATTR_STYLE_SHEET = "styleSheet";
+const static char* ATTR_DEFAULT = "default";
+const static char* ATTR_INTERNAL = "internal";
+const static char* ATTR_OBLIGATORY = "obligatory";
+const static char* ATTR_CONCEALMENT = "concealment";
+const static char* ATTR_USE_RESET = "use_reset";
+const static char* ATTR_GREED = "greed";
+const static char* ATTR_MODIFIED_IN_EDIT = "modified_in_edit";
+const static char* ATTR_MAIN_ARG = "main_argument";
+
+// WDG_INFO properties
+const static char* INFO_WDG_TEXT = FEATURE_TEXT;
+const static char* INFO_WDG_TOOLTIP = FEATURE_TOOLTIP;
+// WDG_DOUBLEVALUE properties:
+const static char* DOUBLE_WDG_MIN = "min";
+const static char* DOUBLE_WDG_MAX = "max";
+const static char* DOUBLE_WDG_STEP = "step";
+const static char* DOUBLE_WDG_DEFAULT_COMPUTED = "computed";
+const static char* DOUBLE_WDG_ACCEPT_EXPRESSIONS = "accept_expressions";
+const static char* DOUBLE_WDG_ENABLE_VALUE = "enable_value";
+
+const static char* DOUBLE_WDG_ENABLE_VALUE_BY_PREFERENCES = "enable_by_preferences";
+
+// WDG_TOOLBOX/WDG_SWITCH properties
+const static char* CONTAINER_PAGE_NAME = "title";
+const static char* CONTAINER_PAGE_ICON = "icon";