A companion answer to try to clear up some terminology.
Specific heat is a derived quantity.
What Are Derived Quantities?
Derived quantities are quantities that are calculated from two or more measurements. Derived quantities cannot be measured directly. They can only be computed. Many derived quantities are calculated in physical science. Three examples are area, volume, and density.
In order to calculate a derived quantity, you must have at least two measurements. Each formal measurement system has a fixed (and rather arbitrary) base unit set. In SI, the base unit set contains seven units - meter, second, kilogram, mole, amp, candela, and degree kelvin. Additional measurements may be required in some particular circumstances such as radian and steridian measurements. But those do not appear as units in the final expression of the derived quantity.
So for specific heat, which is the amount of heat needed to raise one kilogram of something by one degree kelvin, we have units of joules per kilogram per kelvin in SI. Joule is also a derived quantity. In base SI units, it is a kilogram meter squared per second squared. You need measurements of mass in kilograms, temperatures in kelvin, and time in seconds.
One way to calculate specific heat is to measure the mass of a sample and put it in a box with a calibrated resistor wire (premeasured). You measure the starting temp and note the time, switch the current on, measure the current in amps, and the time duration in seconds that you applied the current. Then you measure the final temperature. When combined with the calibrated measurements inside the machine, you have what you need to calculate the specific heat of the material.
So in some way shape or form you must obtain measurements for all the base unit quantities that comprise the derived unit. Often, we can use other derived units to get there quicker. Resistance in ohms is a derived unit, but is usually a known quantity at the outset or measured with an ohmmeter.
Answer to question -
There is no term for what it is you need to measure because that is determined by the device you are using. Machines simplify the process of calculating derived quantities because they already have some of the measurement information needed inside of them. This is what calibration is about.
This is why the term proxy often works when the machine gives you all but one of the measurements needed. You don't need to know anything about the machine, just that it exists and reduces the problem to one measurement. In contrast, if you do know how the machine works, parameter may be a better term, since the machine is no longer a black box, but represents a known algorithm.