---
title: "background"
slug: "background-syntax"
updated: 2022-07-27T22:19:49Z
published: 2022-07-27T22:19:49Z
---

> ## Documentation Index
> Fetch the complete documentation index at: https://code.tag.bio/llms.txt
> Use this file to discover all available pages before exploring further.

# background

## background

**usage: *common* - datatype: *object***

The `background` attribute of a Tag.script specifies the set of entities that comprise the background of the analysis. Only those entities declared in the `background` attribute will be included in the analysis - including all other Tag.script attributes like `focus` and `analysis_variables`. If the `background` attribute is not defined, it will default to all entities in Tag.cortex. The simple form of the `background` attribute is a single categorical variable object.

```
"background": {
  "variable_type": "categorical", //A categorical variable object
  "collection": "cccc", //"cccc" is a valid categorical collection name in Tag.cortex
  "variable": "vvvv" //"vvvv" is a valid variable name in collection "cccc"
}
Alternatively, the background attribute can be any categorical variable object that compiles to a single categorical variable, e.g. "categorical-compound".
```

```
"background": {
  "variable_type": "categorical-compound",
  "operator": "oooo", //"AND" for intersection, "OR" for union
  "criteria": [ 
    {...}, //Two or more categorical variable objects
    {...},
    ...
  ]
}
```