As a follow up to this question, what does the _NET_ mean in X11? From this answer (by me) it seems i3 takes _NET_x to be a superior form of x. But unlike the definition of the non-_NET_ props, I don't see any of them mentioned in the Inter-Client Communication Conventions Manual (ICCM)?

Where is specified the difference between something like

_NET_WM_NAME(UTF8_STRING) = "config (~/.config/i3) - VIM"


WM_NAME(STRING) = "config (~/.config/i3) - VIM"

I found this mention in ICCM,

To prevent conflicts among organizations, additional prefixes should be chosen (for example,_DEC_WM_DECORATION_GEOMETRY).

So this may be an additional ad-hoc prefix, but at what layer is this provided? Is this an Ubuntu thing?


This is an "Additional Window Property", it seems to be not in the ICCM/X11, but an extension called "Extended Window Manager Hints" by the "X Desktop Group" (FreeDesktop.org). The X Desktop Group uses _NET as their organization-prefix.

In their Application Window Properties they're providing a UTF-8 field for the WM_NAME, WM_VISIBLE_NAME, WM_ICON_NAME, and WM_VISIBLE_ICON_NAME. The other fields provided in the organization prefix seem to provide unique information about the window such as

  • type via _NET_WM_WINDOW_TYPE (tooltip, dialog, combobox, menu, splash, etc)
  • state via _NET_WM_WINDOW_STATE (hidden, focused, below, above, fullscreen, etc)
  • parent window _NET_WM_PID
  • And a few more misc things see the docs
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  • 2
    What's with the downvotes? – Evan Carroll Jan 13 '19 at 0:32

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