Quartz Scheduler uses 6 or 7 fields: optional seconds, then minute, hour, day-of-month, month, day-of-week, and optional year. It also supports ?, L, W, and #.
Best-effort conversion
Cronnest maps common Quartz expressions to a 5-field Unix form for explanation and next-run previews. Seconds and year fields are ignored; advanced tokens like L/W/# are stripped. Always verify critical schedules in your Quartz runtime.