server_definitions

The server_definitions method returns the protocol definitions that the server knows about: serialized types, fields, ledger entry types, transaction types, result codes, flags, amendments and, from 2026.10.13-release+4119, the Hook API. Client libraries and tooling use it to encode and decode Xahau binary data without hard-coding definitions.

Request Format

{
    "command": "server_definitions"
}

The response includes a hash of the definitions. Clients that cache the definitions can compare the hash and refetch when it changes.

Response Fields

Field	JSON Type	Description
TYPES	Object	Serialized type names mapped to their type codes.
FIELDS	Array	Every field the server knows, with its type, code and serialization properties.
LEDGER_ENTRY_TYPES	Object	Ledger entry type names mapped to their type codes.
TRANSACTION_TYPES	Object	Transaction type names mapped to their type codes.
TRANSACTION_RESULTS	Object	Transaction result codes mapped to their numeric values.
TRANSACTION_FLAGS	Object	Transaction flags, by transaction type.
TRANSACTION_FLAGS_INDICES	Object	Flag indices for AccountSet (asf*) flags.
features	Object	Amendment IDs mapped to their name, supported, enabled and ledger_enabled status (see Features).
HOOK	Object	The Hook API: functions, keylet types and return codes (see Hook Definitions). (Introduced in 2026.10.13-release+4119.)
native_currency_code	String	The native currency code (XAH).
hash	String	A hash of the definitions.

Features

Each entry in features is keyed by amendment ID and contains:

Field	JSON Type	Description
name	String	The amendment name.
supported	Boolean	Whether this server’s build supports the amendment.
ledger_enabled	Boolean	Whether the amendment is active on the ledger. (Introduced in 2026.10.13-release+4119.)
enabled	Boolean	Whether the amendment is active on this server. This includes amendments forced on by the [features] configuration section (used in standalone and test setups).

Caution: Clients that previously read enabled as “active on ledger” should switch to ledger_enabled. Config-forced amendments that the amendment table does not know about are also listed, by name where possible.

Hook Definitions

(Introduced in 2026.10.13-release+4119.)

The HOOK section lets tooling and SDKs discover the Hook API from the node:

"HOOK": {
    "API": {
        "dice": {
            "return": "int64_t",
            "params": [ { "type": "uint32_t", "name": "sides" } ],
            "amendment": "RNG"
        },
        "accept": {
            "return": "int64_t",
            "params": [
                { "type": "uint32_t", "name": "read_ptr" },
                { "type": "uint32_t", "name": "read_len" },
                { "type": "int64_t", "name": "error_code" }
            ]
        }
    },
    "KEYLET_TYPES": { "HOOK": 1, "...": 0, "MANIFEST": 37 },
    "RETURN_CODES": { "SUCCESS": 0, "OUT_OF_BOUNDS": -1, "...": 0, "TOO_LITTLE_ENTROPY": -46 }
}

Field	JSON Type	Description
API	Object	Every Hook API function this build knows, with its return type and named params. amendment is present only for functions gated by an amendment.
KEYLET_TYPES	Object	The util_keylet keylet type names mapped to their values.
RETURN_CODES	Object	The Hook API return codes mapped to their values.

Note: API lists all functions this build knows, not only those currently enabled. To check whether a function is usable, compare its amendment against the features list.

Because HOOK is part of the definitions, the definitions hash changed in this release. Clients that cache by hash will simply refetch.