A level of design is a hierarchical level which is created whenever any element functions as a component within a specific system.
Levels of design are often at least potentially present whenever systemic components are defined or specified with sufficient strictness to enable valid development apart from their base system. Such valid development could be done by the same agent(s) who created the base model, but it also may (depending on social context) be autonomous or even independent.
When components are autonomously developed, they become extensions of the base level.
Due to the contextuality of levels of design, they may develop in diverse relationships and in any direction. (will add examples)
While levels of design are most basically and generally associated with intentional design processes, they exist in many or most perceptions and descriptions, including reports and recordings.
Optionally, see also Levels of Design in Describing Resources and Systems for extended treatment of this term.