Learn in the textbookRequirements Definition and Design
DefinitionDetailed design (詳細設計) is the design phase that refines the specifications from earlier design into internal specifications detailed enough to write programs.
ExplanationIn the finer naming scheme, the software detailed design (ソフトウェア詳細設計) stage decides the processing steps and data handling for each program to be coded. The results are compiled into design documents that programming then relies on.
AnalogyIt is like construction drawings that add pillar positions and the routes of wiring and piping to the floor plan. They are detailed enough for workers to start building right away.