UNICOM Electric 8 - Manual (Page 29)

Actions->
<Edit>: Configure all items. When finished configuring, press ESC to go
back to the action menu line.
<Save>: Save all configured values.
<Quit>: Exit this page and return to previous menu.
4-4. Protocol Related Configuration
4-4-1. STP
4-4-1-1. STP Enable
This page enables or disables the Spanning Tree function. Press Space
key to select enabled or disabled.