For buyers contracting authority
The line that defines 72212670 is timing, not platform. Choose it when the deliverable is software that has to meet hard response deadlines, deterministic scheduling, real-time control or live alerting, rather than software graded by the machine it runs on.
That is the boundary against the sibling codes. Personal computer (PC) operating system software development (72212650) and Mainframe operating system software development (72212620) classify operating-system work by hardware class. Pick 72212670 instead when the defining requirement is the real-time guarantee, whatever the underlying machine.
A second boundary is general software development (72262000). If the contract builds an ordinary application with no hard timing constraint, it belongs there. Reserve this code for system software whose whole point is responding inside a fixed window. Where one contract bundles real-time development with broader build work, set the primary CPV code by the dominant deliverable, not by the whole package.