From the wonderful RedGuides Wiki

This command is added by MQ2HUD

Syntax Key
Notation Description
Text without brackets or braces Required items
<Text inside angle brackets> Placeholder for which you must supply a value
[Text inside square brackets] Optional items
Vertical bar (|) Separator for mutually exclusive items; choose one
{Text | inside | braces} Set of required items; choose one
Ellipsis () Items that can be repeated
Syntax /backgroundhud {on|off}
Description Turns background updates ON or OFF. When OFF, the HUD will only appear on the active screen, saving CPU cycles on each background client.



See also