You can call the GetDerivedFormulaExplanation API to audit LUSID’s calculation of a particular derived property value, but the LUSID web app offers the best experience.
Consider the following example, of a Holding/MyDPs/Summary derived property with the following formula:
concat(units, ' in instrument ', Properties[Instrument/default/Name], ' at a cost of ', cost.amount)
We might examine the Portfolio Management > Holdings dashboard for a particular portfolio and see the following:
If By tax lots were enabled, we might see a breakdown of individual transactions:
Right-click on any derived property value and choose Explain to understand how LUSID calculates a derived property value:
You can audit the calculation in either Graph view:
…or Code view:
Note that if you do call the GetDerivedFormulaExplanation API for a Holding derived propery then you must specify the subEntityId field with a holding ID. You can optionally add a tax lot ID for a position or a temporary cash holding using the syntax <holding-id>:<tax-lot-id>, for example:
{
"entityType": "Holding",
"scope": "MyPortfolioScope",
"code": "MyPortfolioCode",
"subentityId": "78605785:Txn03/Side2",
"propertyKey": "Holding/MyDPs/Summary"
}