User blog comment:Dr. Satl, M.D./Petit Computer 3 Update?/@comment-9531161-20130930094428/@comment-1595298-20130930182705

You're exactly right. In fact, 9999 lines of code completely filled isn't even allowed; according to the manual there's a character limit of around 520,000 (i.e. half a megabyte). As for editing really large programs, at the very least we have the LIST command that can take you to any line or label instantly.