Appendix D — Event ID Encoding Reference

Event IDs are 64-bit (8-byte) values carried in Producer/Consumer Event Report (PCER) messages and identification messages. This appendix documents the well-known event IDs, broadcast time encoding, train search encoding, and range encoding used by the library.

D.1 Well-Known Events: Auto-Routed

Events in the 0x0100000000xxxxxx range are automatically forwarded by gateways between network segments:

D.2 Well-Known Events: Non-Auto-Routed

Events in the 0x0101xxxxxxxxxxxx range are segment-local and not forwarded by gateways:

D.3 Broadcast Time Event Encoding

Broadcast time events use 8-byte Event IDs where the upper 6 bytes identify the clock and the lower 2 bytes encode the time data or command:

Event ID layout:
Bytes 0-5: Clock ID (identifies which clock)
Bytes 6-7: Command/Data (time, date, year, rate, or control command)

Example: Default Fast Clock, Report Time 14:30
  Clock ID: 01.01.00.00.01.00
  Data:     0E.1E  (hour=14 in bits 12-8, minute=30 in bits 7-0)
  Event ID: 01.01.00.00.01.00.0E.1E

Clock Identifiers

Data Type Ranges (Lower 2 Bytes)

D.4 Train Search Event Encoding

Train search events use the 09.00.99.FF prefix. The lower 4 bytes encode the search address and flags:

Event ID: 09.00.99.FF.xx.xx.xx.xx

Bytes 4-6: Search address encoded as 6 BCD nibbles, MSB first
           Short queries padded with 0xF nibbles
Byte 7:   Flags byte

Train Search Flags

D.5 Event Range Encoding

Event ranges allow a node to express interest in a contiguous block of Event IDs using a single identification message. The range is defined by a base Event ID and a power-of-2 count:

// Range structure
typedef struct {
    event_id_t start_base;              // Starting Event ID
    event_range_count_enum event_count; // Number of consecutive IDs
} event_id_range_t;

Supported range sizes (defined in event_range_count_enum):