Processing the results

The player’s open GUI

Returns the player’s currently open GUI.
If the player does not have a GUI open, it will return <none>.

%players%'s gui
gui of %player%'s

Check whether any GUI is open or not for the player

%players% (has|have) a gui [open]
%players% do[es](n't| not) have a gui [open]

The next GUI slot

Returns the number or letter of the template of the next GUI slot

%guis%'[s] next gui slot[s]
[the] next gui slot[s] of %guis%

Subsequent expressions can only be used in the GUI creation sections and creating an interactive element 

[the] next gui slot

The name GUI inventory

%gui%'s gui(-| )name
gui(-| )name of %gui%

GUI Inventory Size

%gui%'s gui(-| )size
gui(-| )size of %gui%

GUI Template

%gui%'s gui(-| )shape
gui(-| )shape of %gui%

The ability to take items in the GUI

%gui%'s gui(-| )lock(-| )status
gui(-| )lock(-| )status of %gui%

Current, editable GUI

[the] gui

Clicked Slot

[the] gui(-| )raw(-| )slot

The hotkey of the clicked slot

[the] gui(-| )hotbar(-| )slot

GUI inventory that is being edited

[the] gui(-| )inventory

Action inside the GUI

For example, a player made a double click, which caused things to gather in the cursor slot.

[the] gui(-| )inventory(-| )action

Type of click

For example, a player made a click with the Shift key held down.

[the] gui(-| )click(-| )(type|action)

Cursor slot

[the] gui(-| )cursor[(-| )item]

The type of clicked slot

[the] gui(-| )slot(-| )type

The clicked item

[the] gui[(-| )(clicked|current)](-| )item

The expression used instead of the player inside the GUI section

[the] gui(-| )player

Be sure to use this expression inside the GUI or interactive element creation section instead of player, otherwise your code will not work as you expect it to.
Using player outside these sections may result in referencing the wrong player or causing unexpected behavior in your GUI logic.

Players who have a GUI open

[the] gui(-| )(viewer|player)s

ID of the clicked slot

[the] gui(-| )slot(-| )id

Subsequent expressions can only be used in the closing GUI section

Cancel the closure

Prevents the player from closing the GUI by automatically reopening it, preserving the GUI’s parameters

cancel [the] gui clos(e|ing)

Allow closure

Allows the player to close the GUI

uncancel [the] gui close(e|ing)