Notion keyboard reference:

META key

All keybindings are activated by pressing the META key, which by default is the 'windows' key.
The 'grey' bindings are activated by pressing ALTMETA (by default pressing Shift while holding META).

Mod4+WGo to frame above current frame.
Mod4+RRaise focused object, if possible.
Mod4+AGo to frame left of current frame.
Mod4+SGo to frame below current frame.
Mod4+DGo to frame right of current frame.
Mod4+FGo to previous
Mod4+graveToggle scratchpad.
Mod4+ZSwitch to previous object (workspace, full screen client window) within current screen.
Shift+Mod4+ZGo to previous screen on multihead setup.
Mod4+XSwitch to next object (workspace, full screen client window) within current screen.
Shift+Mod4+XGo to next screen on multihead setup.
Mod4+F9Create a new workspace of chosen default type.
Mod4+F12Display the main menu.
Client windows
Shift+Mod4+CKill client owning the client window.
Shift+Mod4+spaceNudge the client window. This might help with some programs' resizing problems.
Mod4+ReturnToggle client window group full-screen mode
Mod4+TabSwitch to next object within the frame.
Shift+Mod4+TabSwitch to previous object within the frame.
Mod4+RBegin move/resize mode.
Mod4+EAttach tagged objects to this frame.
Shift+Mod4+EQuery for a client window to attach ('nick').
Mod4+commaMove current tab to the right within the frame.
Mod4+periodMove current tab to the left within the frame.
Shift+Mod4+WSplit current frame vertically up.
Shift+Mod4+ASplit current frame horizontally left.
Shift+Mod4+SSplit current frame vertically down.
Shift+Mod4+DSplit current frame horizontally right.
Mod4+QToggle tag of current object.
Mod4+F2Run a terminal emulator.
Mod4+F3Query for command line to execute.
Mod4+F7Query for keybinding.
Mod4+F10Query for a client window to go to.
Mod4+F11Display context menu.
Mod4+CClose current object.
Mod4+spaceDetach (float) or reattach an object to its previous location.