Definition: Event and history calibration

Event-time calibration. For a reading at the fixed event $e$, an input is exactly calibrated when

Thus the returned label is the coordinate of the reading event.

History-label calibration. Choose a finite event map

A readout at an independently specified event $e_{\mathrm{r}}$ returns the label of $\kappa (k)$. It need not return $T(e_{\mathrm{r}})$. In the examples below all $\kappa (k)$ are earlier points on the sender's static worldline.