Is the information available online about \"staged control\" already outdated?

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Search the Internet for information or papers on cascade control, including some textbooks available in bookstores; they all include a diagram like the one below. I would like to ask: regarding the X-axis in that diagram, which represents the regulator output of 0.02–0.1 MPa, is this not the output signal of pneumatic regulators from a long time ago? DCS is now basically used, and the output should be 4-20mA. The implementation of division is to divide the 4-20mA output from a single AO into two segments, which are then assigned to two separate AOs. (This is equivalent to doubling the resolution of the original AO output), but these two AO outputs remain at 4-20mA; the electrical valve positioners and control valves connected to them are no different from those in a single-loop system. The spring range of the control valve is also 20-100 kPa. I’m not sure if my understanding is correct