---
title: "Parts Cross-Reference Data: Keeping Your Fitment Catalog Accurate"
url: https://www.uncap.com/post/parts-cross-reference-data
author: "Denis Dyli"
published: 2026-08-05
updated: 2026-08-11
summary: "Parts cross-reference data maps competitor and OEM numbers to your SKUs so buyers searching any number land on the right part. Every aftermarket catalog needs three mappings, OEM to aftermarket, competitor to equivalent, and supersession chains, and bad data in any of them turns directly into wrong-part orders."
---

# Parts Cross-Reference Data: Keeping Your Fitment Catalog Accurate

> Parts cross-reference data maps competitor and OEM numbers to your SKUs so buyers searching any number land on the right part. Every aftermarket catalog needs three mappings, OEM to aftermarket, competitor to equivalent, and supersession chains, and bad data in any of them turns directly into wrong-part orders.

## Frequently asked questions

### What is a parts cross-reference?

A cross-reference, also called an interchange, is a mapping between equivalent part numbers: an OEM number to its aftermarket replacements, one brand's number to another's, or a superseded number to its current version. Catalogs use these mappings to resolve whatever number a buyer searches to the right product.

### What is the difference between a cross-reference and an interchange?

In practice they are the same concept and the terms are used interchangeably. "Interchange" is the older industry term, common in the used and remanufactured parts world; "cross-reference" is more common in new-parts catalogs and in the PIES data standard's interchange segment.

### What is a part number supersession?

A supersession is when a manufacturer discontinues a part number and replaces it with a new one. Supersessions chain over time, so a catalog has to follow each number to its current end point, or buyers searching an older number they have used for years will find nothing.

### Why do wrong cross-references cause returns?

Because the catalog asserted an equivalence the physical parts do not honor. A near-match mapped as an exact match produces an order that fails at installation, and the buyer reasonably holds the seller responsible. Bad interchange data and bad fitment data produce the same outcome through different doors: a part that does not fit.

### Can buyers search by OEM number on a Shopify parts store?

Yes, when cross-reference data is loaded and connected to search, any known equivalent number resolves to the right product. That mapping layer is implementation work on top of the platform, built from the interchange data your brands publish and your own reconciliation of it.