+/// Note 1.
+///
+/// Please note that IsCalibrated and IsChargeInFC are two
+/// concepts closely related, but not equivalent, at least for SDigits.
+///
+/// For instance a SDigit can have its charge in fC but not being calibrated.
+///
+/// { SDigits coming from a simulation are yet to be merged (i.e. the
+/// SDigitStore can contain several SDigits objects per channel), so, while
+/// their charge is in femto-coulomb, they are not calibrated (e.g. pedestal
+/// is not subtracted yet). }
+///
+/// Conversely, a calibrated (s)digit always has its charge in fC.
+///