---
title: "Packet 60: MapDataValidation"
description: "Exchanges the map file CRC. The server answers with its authoritative file checksum before streaming."
canonical: "https://aosplay.net/protocol-168/packets/60"
markdown: "https://aosplay.net/docs/protocol-168/packets/60.md"
last_updated: "2026-07-16"
protocol: "Ace of Spades Battle Builder 168"
packet_id_decimal: "60"
packet_id_hex: "0x3C"
direction: "Both"
family: "Map sync"
implementation_status: "Handled + sent"
evidence: "Live-verified"
wire_size: "5 bytes"
---

# Packet 60: MapDataValidation

> Exchanges the map file CRC. The server answers with its authoritative file checksum before streaming.

- **Decimal ID:** 60
- **Hex ID:** 0x3C
- **Direction:** Both
- **Family:** Map sync
- **Status:** Handled + sent
- **Evidence:** Live-verified
- **Wire size:** 5 bytes

## Exact wire layout

The application packet ID is the first byte. The remaining rows are in decode order. Byte sizes exclude ENet headers, wrapper prefixes, LZF chunk framing, and compression effects.

| # | Field | Encoding | Bytes | Purpose | Condition |
| ---: | --- | --- | ---: | --- | --- |
| 0 | `packet_id` | u8 | 1 | Always 60 (0x3C). | — |
| 1 | `crc` | i32 LE | 4 | Signed 32-bit map checksum used by the validation handshake. | — |

## Encoding conventions

- `LE` means least-significant byte first.
- `fixed16` is two-byte sign-magnitude at 1/64 precision.
- `orientation16` uses the measured 1/8192 orientation mapping.
- NUL strings consume their encoded byte length plus one `00` terminator.
- Counted arrays repeat immediately in the documented order.

## Related resources

- [HTML packet page](https://aosplay.net/protocol-168/packets/60)
- [Complete packet catalog](https://aosplay.net/protocol-168/packets)
- [Packet catalog in Markdown](https://aosplay.net/docs/protocol-168/packets.md)
- [Protocol 168 guide](https://aosplay.net/protocol-168)