Every single line of the 420,000 was completely annotated, showing every time it had ever been changed. Why, when, how, and by whom. Every change was rigorously linked to some severe dictation in the design specs. Literally everything that had ever happened to this vast program, down to the tiniest detail, was recorded in a giant master history. And since this code re-used some fully tested code from earlier spy-sats, the reports stretched back some thirty solid years.