---
title: "What is the unknown instrument, or LUID_ZZZZZZZZ?"
slug: "what-is-the-unknown-instrument-or-luid-zzzzzzzz"
updated: 2024-08-20T07:42:38Z
published: 2024-08-20T07:42:38Z
canonical: "support.lusid.com/what-is-the-unknown-instrument-or-luid-zzzzzzzz"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://support.lusid.com/llms.txt
> Use this file to discover all available pages before exploring further.

# What is the unknown instrument, or LUID_ZZZZZZZZ?

By default, LUSID operates a ‘data load first’ policy, so [transactions](/v1/docs/transactions) and other data items are upserted and exceptions flagged for subsequent remediation, without interrupting critical processes.

> **Note**: You can [increase the level of validation](/v1/docs/validating-transactions#increasing-the-level-of-validation-to-reject-unresolved-transactions) to *reject* transactions that do not resolve to instruments.

Every instrument mastered in LUSID has at least one [identifier](/v1/docs/understanding-instrument-identifiers). When you book a transaction (and some other types of data) into LUSID, you must specify at least one instrument identifier in your API upsert request. A set of rules governs how LUSID [automatically resolves](/v1/docs/how-does-lusid-resolve-data-to-instruments) ingested data items to instruments.

There may be circumstances in which LUSID cannot match a particular data item to an instrument. To prevent the data load operation failing, LUSID automatically resolves this item to the unknown instrument instead. This is a built-in instrument with a [LUSID Unique ID](/v1/docs/what-is-a-lusid-instrument-id-or-luid) of `LUID_ZZZZZZZZ`.

You should take steps to [manually resolve unknown instruments](/v1/docs/manually-resolving-data-mapped-to-luid-zzzzzzzz).

## A note on the unknown currency

In addition to `LUID_ZZZZZZZZ`, LUSID has a built-in unknown currency. This has a LUID of `CCY_ZZZ`.

Unlike non-currency instruments, LUSID does not automatically map unknown cash transactions to the unknown currency. This is because your LUSID domain is [prepopulated with a basket of currencies](/v1/docs/how-do-i-create-a-currency), and so booking cash transactions is an operation much less likely to fail. You are able to create a new currency (perhaps to represent a cryptocurrency), but it is not anticipated that this will be a common operation.

You can manually assign the unknown currency to a cash transaction or other data item when you upsert it into LUSID if you wish.