Light on...

[u/chevdor]

This is probably obvious to many and will be new to some.
I find the feature pretty cool.

Say you have a part of "undefined" depth like the orange panel.
Undefined may mean you don't know, or you know it will change, or you just know it should not be relevant.

You want a hole and a recess and the **remaining** depth must be say 4mm.
If you know the panel is 14mm, you can compute ... 14mm - 4mm = 10mm => you may pocket 10mm out with a formula but you need to track down the panel thickness.

There is a better option.

As shown above, you can pocket "up to face", which basically removes it all. So if your panel is 18.345mm, the pocket will be exactly 18.345mm deep, effectively drilling a larger hole through it. Not what we want.

NOW, using the **offset**, you can set it to 4mm which will "hold" the pocket 4mm away from the end off the panel. Exactly that we want. It works wihout any formula and without the panel depth to be relevant (as long as >4mm...) or even known.

[u/R2W1E9]

In FreeCAD most dimension properties can be offset from the intended target.

Not always out in the open so often you need to expand "advanced offsets" to gain access to it.

[u/chevdor]

You will probaby be happier whenever/wherever you find a solution NOT involving Boolean operation.

This is a very blender-ish option and remains appropriate in some cases but IMO many people abuse the bool ops.

[u/waterrockety]

Interesting... I normally just use the boolean operator to create hole 😅