Enabling this option will extend the frequency of the test selected. It does not change the limit line of the selected standard.
This is also true for Channel measurements.
The feature is found by rotating the dial on the DTX CableAnalyzer to SETUP and selecting Instrument Settings.
Why doesn't Category 6 / Class E run to 900 MHz on "Extended"?
These standards are available in the DTX-1200, a 350 MHz tester. The concept behind "Extended" is to run the maximum frequency whilst keeping it simple. Extended on the DTX-1200 and DTX-1800 is the same for the sake of simplicity.