This makes modifier or layer keys behave a bit differently.
Let's use the "One-shot Shift" as an example:
1. If you hold it, it will work as usual; it will make all letters capitalized.
2. If you tap "One-Shot Shift" once, and then hit the keys "a" and "b" you will type "Ab". The shift key is activated for the next key ONLY.
3. If you double-tap "One-Shot Shift", it will lock the modifier. Everything you type will be in capital letters as if you had Caps Lock activated. If you tap it again, it will be deactivated.
Imagine you are in Layer 0 and you have a "One-Shot Layer 1" key:
1. If you hold the key, you shift to Layer 1. Releasing the key will bring you back to Layer 0.
2. Single ta: It acts as a ‘BoomerangLayer’. This will bring you to Layer 1 but after you press any key on that layer, you will be brought back to the previous layer.
3. Double-tap: It acts as ‘MoveToLayer’. You are locked on Layer 1 until you tap the One-Shot Layer 1 key again.
Reminder: When assigning the One-Shot Layer key, make sure that the same key on the other layer is assigned as the same One-Shot Layer key (eg: Layer 1 has OSL 2 on a key, and Layer 2 has OSL 2 on that same key).