The first letters in PPC and in SCM have extended meanings. PPC software packages no longer relate solely to production or supply, but rather as ERP software to the entire logistics chain from sales, production, and procurement, right through to distribution and maintenance. In addition, new requirements have arisen in association with reuse and recycling. Thus, it is logistics, rather than just production, that represents the overall function within the company. For this reason we now speak of logistics software, by which we mean comprehensive computerization of the way in which the data and control flow is handled within a company’s logistics function. It is also no longer possible to equate PPC software with MRP II packages since it incorporates just-in-time, variant-oriented, and processor-oriented concepts and with varying levels of quality, just like the MRP II concept. Similarly, SCM software is as useful for demand chain planning.............................
The letter “P” in PPC or APS for “planning”: Neither a PPC soft-ware nor an ERP software nor a SCM software nor an APS software does planning in the strict sense of the word. It simply supports the planning function, for example, by showing the availability of components and capacity along the time axis. Then comes the planning, e.g., action to change stocks, capacity, or order dates. Every attempt to hand this planning step over to the computer, e.g., through the use of simulation software, has ultimately failed, because the software is unable to cope with the day-to-day problems of decision making, either because the relevant parameters were not all known or because they could not be reliably shown along the time axis....................
The letter “C” in PPC for “control” or “S” in APS for “sche-duling”: Neither PPC software nor ERP software nor SCM software nor APS software controls or schedules anything in the strict sense of the word. In the best-case scenario it merely provides a snapshot of the current status of order processing in the various domains in the company and recommendations options for control or regulation. The actual control or scheduling task still has to be carried out by people. Production and procurement in the manufacturing and service industries cannot be compared to the control of a machine or production system, since the equation inevitably includes people whose behavior finally cannot be predicted or simulated. On the other hand, although the inclusion of people as a production factor appears to be a disadvantage, it is also an advantage: no automated control system will ever be able to match the capabilities and potential of a human in control or scheduling, however flexible and autonomous it might be.