+int specifier_string(char specifier, void *data, void *userdata, char **ret);
+
+int specifier_machine_id(char specifier, void *data, void *userdata, char **ret);
+int specifier_boot_id(char specifier, void *data, void *userdata, char **ret);
+int specifier_host_name(char specifier, void *data, void *userdata, char **ret);
+int specifier_kernel_release(char specifier, void *data, void *userdata, char **ret);