SI units: slope vs. rate

[tobolar]

There are defined units indicating change of the unit over time. They have a suffix "slope" or "rate".

The question is:

1. Shouldn't this be unified?
2. Shall such units even be a part of Units.SI at all? See https://github.com/modelica/ModelicaStandardLibrary/pull/4103/files#r1152856158

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Slope:

• Modelica.Units.SI.CurrentSlope
• Modelica.Units.SI.TemperatureSlope
• Modelica.Units.SI.VoltageSlope

Rate:

• Modelica.Units.SI.MassFlowRate
• Modelica.Units.SI.VolumeFlowRate
• Modelica.Units.SI.EntropyFlowRate
• etc.

[HansOlsson]

To me the first answer is 'No', and they are different even if the units are similar:

• Slope indicates the derivative of a curve (w.r.t. time).
• FlowRate indicates the rate at which the quantity flows past something (per unit of time). Thus a MassFlowRate doesn't necessarily indicate that the mass changes somewhere (especially not in a closed system), just that it flows past something (a valve etc).

With that line of thinking Current (not CurrentSlope) is a ChargeFlowRate.
So derivatives have slopes and connectors may contain flow-rates.