---
title: "How does LUSID resolve data to instruments?"
slug: "how-does-lusid-resolve-data-to-instruments-1"
updated: 2025-04-28T07:20:35Z
published: 2025-04-28T07:20:35Z
canonical: "support.lusid.com/how-does-lusid-resolve-data-to-instruments-1"
---

> ## 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.

# How does LUSID resolve data to instruments?

When you upsert [transactions](/v1/docs/transactions) and other data items to LUSID, you must specify at least one [identifier](/v1/docs/understanding-instrument-identifiers) mapping each item to an instrument mastered in LUSID.

For example, a simple equity such as [BP PLC $0.25 shares traded in London](https://www.londonstockexchange.com/stock/BP./bp-plc/company-page) might have any of the following identifiers:

- A FIGI of `BBG000C05BD1`
- A SEDOL of `0798059`
- An ISIN of `GB0007980591`
- A ClientInternal of `bp-plc-ldn` (this represents your internal security database for demonstration purposes)

> **Note:** Identifiers are classed as either *unique* and identify exactly one instrument per [instrument scope](/v1/docs/understanding-instrument-scopes) (for example FIGI), or *non-unique* and can identify more than one instrument per scope (such as ISIN). [More information](/v1/docs/what-are-unique-and-non-unique-identifiers).

For example, you might [upsert transactions](/v1/docs/how-do-i-create-or-update-a-transaction) into LUSID from a system that identifies BP PLC $0.25 shares using a FIGI:

```json
[
  {
    "transactionId": "txn-upsert-1",
    "type": "StockIn",
    "instrumentIdentifiers": {
      "instrument/default/Figi": "BBG000C05BD1"
    },
    ...
```

Meanwhile, you might [upsert corporate actions](/v1/docs/how-do-i-upload-corporate-actions-to-a-corporate-action-source) from a system that identifies BP PLC $0.25 shares using an ISIN:

```json
"transitions": [
   {
      "inputTransition": {
         "instrumentIdentifiers": {
            "instrument/default/Isin": "GB0007980591"
             ...
```

LUSID must resolve these data items to the same BP PLC $0.25 instrument mastered in LUSID in order to guarantee a consistent economic impact.

By default, LUSID operates a ‘data load first’ policy, so 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 if you prefer.

For each data item you upsert, LUSID examines the instrument identifiers in the API request and performs the following steps in turn until a matching instrument is found:

**Step 1:** LUSID determines the instrument scope in which to look. If a transaction is booked into a portfolio with a custom instrument scope, LUSID performs steps 2 and 3 in that scope. If not, LUSID automatically falls back to the built-in `default` instrument scope.

**Step 2**: LUSID examines the unique identifiers specified in the API request in the following order: `<Your unique identifiers ie. Figi> → ClientInternal → Currency → LusidInstrumentId`. If the request contains a unique identifier *and* a matching instrument is found in the instrument scope, LUSID resolves to that instrument.

**Step 3**: If not, LUSID examines the non-unique identifiers:

1. If the API request has one or more non-unique identifiers and together they match a single instrument exactly, LUSID resolves to that instrument.
2. If no single exact match is found, LUSID cycles through the non-unique identifiers in the following order: `Sedol → Isin → Cusip → RIC → <Other identifiers in alphabetical order>`:
  1. If the non-unique identifier being examined matches a single instrument, LUSID resolves to that instrument.
  2. If the identifier matches either zero instruments *or* two or more, LUSID ignores it and tries the next non-unique identifier, if there is one.

If a matching instrument cannot be found in a custom instrument scope, LUSID repeats **Step 2** and **Step 3** in the `default` scope. If a matching instrument *still* cannot be found, LUSID maps the data item to the unknown instrument (`LUID_ZZZZZZZZ`). This is important as it prevents the data load operation failing, but you should take steps to [manually resolve unknown instruments](/v1/docs/manually-resolving-data-mapped-to-luid-zzzzzzzz).

> **Note:** LUSID does *not* map unknown cash transactions to the [unknown currency](/v1/docs/what-is-the-unknown-instrument-or-luid-zzzzzzzz#a-note-on-the-unknown-currency).

The following flow diagram summarises the mapping logic for (non-currency) instruments within the `default` scope:

![](https://cdn.document360.io/d575ad81-c0ed-4980-bbd1-d59ac5c3de82/Images/Documentation/image.png)