---
sourceDocument: Yokohama Finance and Supply Chain
sourceDocumentLink: https://servicenow-prod.fluidtopics.net/r/yokohama/source-to-pay-operations

 Release :

    - yokohama

ft:locale :

    - en-US

ft:publication_title :

    - Yokohama Finance and Supply Chain

ft:clusterId :

    - stpop

bundleId :

    - stpop

workflow :

    - Employee


---

# Rules based engine

# Rules based engine {#ariaid-title1}

* Release version: Yokohama
* 
* Updated April 7, 2025
* 
* ![](https://www.servicenow.com/docs/portal-asset/ico-clock) 1 minute to read

The rule based engine maps the invoice line with purchase order line using fields such as unit price, delivered unit price, exact description, exact amount and amount round off.

The digitized invoice in accepted state moves to suspected duplicate state where the AP specialist verifies if the invoice is duplicate or not. When the invoice is confirmed to be not duplicate, the state of the invoice changes to
received. The rules-based engine maps the fields in invoice such as unit price, derived unit price, exact description, exact amount and amount round off with the purchase order lines. If the invoice fields doesn't match with any of the
fields in the purchase order lines, then the invoice state changes to matching error.

**Related concepts**   

* [Invoice ingestion using Application programming interface (API)](https://servicenow-prod.fluidtopics.net/m9Kb8pn598jiG31ZgeI7tw "The invoice ingestion API enables customers to ingest bulk AP invoices from external systems such as supplier billing systems, buyer network, and OCR solutions, supplier networks into APO. The supported payload formats are cXML, JSON and XML.")
* [Work with invoices](https://servicenow-prod.fluidtopics.net/vpZfIG38U8aiGCaQHyyuDQ "Invoices are generated for a payment against a purchase order. The Accounts Payable Specialist [sn_ap_apm.accounts_payable_specialist] can access all the invoices and take required actions to process the invoices in Source-to-Pay Workspace.")
* [Invoice processing cases](https://servicenow-prod.fluidtopics.net/NoqhBRYN5hAl9N4lAyFhkg "Typically, Accounts Payable Operations integration with Document Intelligence automatically creates the invoice processing case by extracting data from the invoice that you receive as an attachment via email. However, the Accounts Payable Specialist may need to manually create a new invoice or update details of a partially created invoice in situations where the automated invoice creation process encounters issues or is not available.")
* [Invoice exceptions](https://servicenow-prod.fluidtopics.net/IyXgSahnO3KZN8nsBjtBXw "Invoice exceptions are discrepancies identified during invoice processing that must be resolved before payment, such as missing information, tax variances, or supplier issues.")
* [Tolerance Rules and Variances for invoices](https://servicenow-prod.fluidtopics.net/ULJvN5hmmS8PEvCIg4jQzA "Tolerance rules define the limits set on an invoice to determine the permissible amount of variance that can be applied to an invoice before the invoice total exceeds the tolerance limit.")
* [Invoice approvals](https://servicenow-prod.fluidtopics.net/vrNSVQBVP03wVQyX1~ze6w "Invoices with the No exceptions found status are eligible for approval.")  
**Related tasks**   

* [View invoice documents in the Source-to-Pay Workspace](https://servicenow-prod.fluidtopics.net/~wWYOVX7SO2X3zd9k1mNkA "View the invoice documents directly in the Source-to-Pay Workspace using Document Viewer without having to download them.")