ZWave Configuration

This is a basic question about how Z-Wave Configuration is managed by Home Assistant.

Background: Devices support the ability to read and write configuration parameters. HA provides UI to set the parameters in the ZWave Integration Panel.

Question: When I am in Home Assistant / Z-Wave Integration / Select a node / Select a configuration parameter and it displays a value. Is Home Assistant reading the parameter(s) from the devices - at that moment in time and placing those in the parameters value edit box? Or is it displaying the value that was last set by me in the UI? Or a cached value? Or a default value from the XML file?

Question: How does this relate to using the “Save Configuration” button?