The mimeType tells Relic and the browser what kind of file a PhotoRecord holds — for example "image/jpeg" for a standard camera photo or "image/tiff" for a high-resolution plan scan. This matters because it determines how the image is rendered and served: a viewer needs to know the format before it can display the bytes pointed to by filePath. The field is captured at upload alongside filename and sizeBytes, and it is required so every stored image is correctly typed.
Technical section
Data model, API, and internals — visible to developers.