Optional
indexA numeric index which tracks this bindings position during form rendering
The KeyboardEvent#code value from
The Keyboard logical code if universal mode is enable (it is code otherwise) https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/code/code_values
Optional
modifiersAn array of modifiers keys from foundry.helpers.interaction.KeyboardManager.MODIFIER_KEYS which are required for this binding to be activated
A Client Keybinding Action Binding