The Problem

You can stack a block by typing e.g. north-west, or facing diagonally.

You cannot stack a block by typing e.g. north-west-up (diagonally up).

A Solution

Allow pairing cardinal direction with up/down when stacking for extra vertical option.

Alternatives

.//line may be inconvenient especially when the end-point of a line is unknown, only the start point.

Manual placing and copy pasting takes longer.

Anything Else?

No response

pass a vector directly. see //help stack.