Editing Comparison of operating systems (section)

== Nomenclature ==
The nomenclature for operating systems varies among providers and sometimes within providers.
For purposes of this article the terms used are;
;kernel
:In some operating systems, the OS is split into a low level region called the kernel and higher level code that relies on the kernel. Typically the kernel implements processes but its code does not run as part of a process.{{disputed inline|Proposed nomenclature section|date=November 2023}}
:;hybrid kernel
:;monolithic kernel
;Nucleus
:In some operating systems there is OS code permanently present in a contiguous region of memory addressable by unprivileged code; in IBM systems this is typically referred to as the nucleus. The nucleus typically contains both code that requires special privileges and code that can run in an unprivileged state.  Typically some code in the nucleus runs in the context of a dispatching unit, e.g., address space, process, task, thread, while other code runs independent of any dispatching unit.  In contemporary operating systems unprivileged applications cannot alter the nucleus.

License and pricing policies also vary among different systems. The tables below use the following terms:
;[[BSD licenses|BSD]]

:'''BSD licenses''' are a family of [[permissive free software license]]s, imposing minimal restrictions on the use and distribution of covered software.
;bundled
:The fee is included in the price of the hardware
;bundled initially
:The fee is included in the price of the hardware but upgrades require an additional fee.
;[[GNU General Public License#Version 2|GPL2]]
;[[GNU General Public License#Version 3|GPL3]]
;Per user
:The fee depends on the maximum number of users concurrently logged on.
;[[Million service units|MSU]]
:The fee depends on the resources consumed by the user
;MULC
:Measured Usage License Charges
;PSLC
:Parallel Sysplex Software Pricing