> For the complete documentation index, see [llms.txt](https://docs.wellcomecollection.org/catalogue-pipeline/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.wellcomecollection.org/catalogue-pipeline/combining-records-from-multiple-sources/why-do-we-combine-records.md).

# Why do we combine records?

Sometimes information about an entity is split across multiple source catalogues.

For example, a box of papers in the archive might:

* have an archive record in CALM (which is the "canonical" record)
* have a library record in Sierra (so it can be [viewed in the library](https://wellcomecollection.org/pages/YA64vRMAACAAgRjZ#requesting-an-item-to-view-in-the-library))
* have a digitised copy in METS (so it can be viewed online)

We combine these records into a single work so that all the information is on one page. This makes it easier for researchers to find everything we know about a work.

(There are instances in the past where somebody found the online record for a physical object, and travelled to see it in the library in-person, unaware that we had a digitised copy.)