diff --git a/System-configuration.md b/System-configuration.md
index 69f0df6..19aa722 100644
--- a/System-configuration.md
+++ b/System-configuration.md
@@ -55,6 +55,8 @@ of the particular worker instance.
   set in job configuration, defaults from worker config will be used. In such
   case the worker's defaults will be set as the maximum for the job. Also,
   limits in job configuration cannot exceed limits from worker.
+- _max-output-length_ -- used for `tasks.{task}.sandbox.output` option, defined
+  in bytes
 
 ### Example config file