On 2009-09-09, Leon wrote:

replied with what is half of 5.3mm. YOU gave the answer but tried with out
success to show me a ruler with that marking.

That's because NO ONE! makes a RULE in that small a graduation, in
either Imperial or Metric. They don't make it cuz no one can use it!!
There are other measuring instruments that can easily make that
measurement in metric. What don't you understand?

nb