How set 'left opt' key to BTTShortcutModifierKeys?

I wanted to set a shortcut left opt + / but could not find the left opt key.
How set 'left opt' key to BTTShortcutModifierKeys?

1048576  cmd
131072   shift
1179648  shift+cmd
1441792  shift+control+cmd
524288   opt
655360   opt+shift
1703936  opt+shift+cmd
1572864  opt+cmd
262144   ctrl
1966080  ctrl+opt+shift+cmd
786432   ctrl+opt
1835008  ctrl+opt+cmd
917504   crtl+opt+shift
1310720  ctrl+cmd
393216   crtl+shift
8388608  fn
8912896  fn+opt
9961472  fn+opt+cmd
9043968  fn+opt+shift
10092544 fn+opt+shift+cmd
8650752  fn+ctrl
9699328  fn+ctrl+cmd
9175040  fn+ctrl+opt
10354688 fn+crtl+opt+shift+cmd
8781824  fn+crtl+shift
9830400  fn+crtl+shift+cmd
9568256  fn+shift+cmd
9437184  fn+cmd

Activate left/right differentiation, then record the shortcut:

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