# Defining the taxonomy

> Define the taxonomy structure in the Flow Extract node covering the relationship between fields (the data points to be extracted) and field groups (a means of grouping fields under a single concept for processing).

Start by identifying all data points or fields that you want to extract from the documents. Then, organize the fields into a coherent structure using field groups. The fields defined under a field group can be predicted multiple times as different instances of that field group.

:::note
A taxonomy (an extraction schema) is a collection of all fields a model is prompted to extract, structured in a hierarchical manner using field groups.
:::

## Example of an extraction schema

Figure 1. Defining the extraction schema

![The image shows an example of defining the extraction schema.](https://dev-assets.cms.uipath.com/assets/images/ixp/ixp-the-image-shows-an-example-of-defining-the-extraction-schema-563017-eaba91b3.webp)

Figure 2. Example of an extraction schema

![The image shows an example of an extraction schema.](https://dev-assets.cms.uipath.com/assets/images/ixp/ixp-the-image-shows-an-example-of-an-extraction-schema-563021-3447ba37.webp)