+Trend compliance metrics are targeted to provide an indication of trend
+changes, and hint at their reliability.
+
+There is a difference between compliance metric names used in this document,
+and column names used in :ref:`Dashboard` tables and Alerting emails.
+In cases of low user confusion risk, column names are shortened,
+e.g. Trend instead of Last Trend.
+In cases of high user confusion risk, column names are prolonged,
+e.g. Long-Term Change instead of Trend Change.
+(This document refers to a generic "trend",
+so the compliance metric name is prolonged to Last Trend to avoid confusion.)
+
+The definition of Reference for Trend Change is perhaps surprising.
+It was chosen to allow both positive difference on progression
+(if within last week), but also negative difference on progression
+(if performance was even better somewhere between 3 months and 1 week ago).
+
+In the table below, "trend at time <t>", shorthand "trend[t]"