code/__DEFINES/hud.dm

HUD_STYLE_STANDARD	Standard hud
HUD_STYLE_REDUCED	Reduced hud (just hands and intent switcher)
HUD_STYLE_NOHUD	No hud (for screenshots)
HUD_VERSIONS	Used in show_hud(); Please ensure this is the same as the maximum index.
APPEARANCE_UI_IGNORE_ALPHA	Used for progress bars and chat messages
APPEARANCE_UI	Used for HUD objects
PLANE_GROUP_MAIN	The primary group, holds everything on the main window
PLANE_GROUP_POPUP_WINDOW	A secondary group, used when a client views a generic window

Define Details

Used for HUD objects

Used for progress bars and chat messages

No hud (for screenshots)

Reduced hud (just hands and intent switcher)

Standard hud

Used in show_hud(); Please ensure this is the same as the maximum index.

The primary group, holds everything on the main window

A secondary group, used when a client views a generic window