What is the unit of the numbers?

It looks to me they are relative number respect the
upper right corner and they are in inches.

Added after 3 minutes:

For example:

The left lower corner is a microstrip TxL
with a width of 1.010 - 0.990 = 0.020 inches.
The location is in reference to the right upper
corner of (2.000, 3.150).

This reference system is frequently used in mechanical engineering layouts. By referencing all dimensions to one point, the manufacturing errors do not accumulate across the piece.

OK! I understood! THANK YOU ALL!