Hi Anis,

re: Also I need to know the location of a "vertex".

Just use the exact same technique that I mentioned in the previous message (here)

Again - that is to just run any command that picks points within it, for example the line command.

Move your mouse to that vertex of the box, and then the active point will snap on to it - if it doesn't then it means that you have turned "Object Snap" off - turn it on again in that case by clicking on it in the bottom toolbar so that it is highlighted in orange.

When the point currently being drawn is snapped on to that vertex (it will display as "end" since it is at the end of an edge), then the xyz control will hold the value that you want.

- Michael