Yes, but they actually only draw grid but don't prints the value of X-Y coords relative to the starting point they are relative too.
For example.
If I wants something like:
/addon_name UIParent 'CENTER'
it should prints something like the screenshot I attach (numbers are not probably correct but just to give the idea :-)
But probably the numbers on axis will looks differently if I use something like:
/addon_name UIParent 'TOPLEFT'
The positive Y number will disappears and will not be printed ...
But I really don't know also if the starting params are enough to start ... :-/
BTW, thanks again for attention and for your kind reply.