# Clock, Logging & Persistence (S13-S15)

## §13 — Real-time clock & time synchronisation

As a software E-SDC there is no dedicated hardware RTC. Time accuracy is maintained by **NTP synchronisation** against the server provided by FRCS (set via `SetTimeServerUrl`), performed **hourly** — well within the 48-hour requirement. Between syncs the host system clock is the time source. This is the documented alternative to a hardware RTC for an application-based E-SDC.

## §14 — Logging

XPOS ESDC records the required error events: invoice, APDU, TaxCore, internal, initialization, fiscalization, audit and time-synchronisation errors. Log characteristics:

- **Chronological**, timestamped in local time to the second.
- **Human-readable** plain-text daily files, exportable from the UI ("Export logs").
- **Rolling** — daily files retained for the last 30 days; older files removed automatically.
- **Isolated** — logs live in a separate folder and do not affect invoice/package storage.

## §15 — Persistence & offline capacity

Invoice records and encrypted audit packages are stored in a local embedded database that survives power loss and restart (non-volatile). No power is required to preserve fiscal data.

**Offline capacity:** an audit package is approximately 3–5 KB, giving at least **~100,000 unsent invoices per GB** of free storage. The device therefore sustains extended offline operation, reporting automatically once connectivity returns.