---
title: Flux language specification
description: >
  Covers the current and future Flux functional data scripting language,
  which is designed for querying, analyzing, and acting on data.
menu:
  v2_0_ref:
    name: Flux specification
    parent: Flux language
weight: 103
v2.0/tags: [flux]
---

The following document specifies the Flux language and query execution.

{{% note %}}
This document is a living document and may not represent the current implementation of Flux.
Any section that is not currently implemented is commented with a **[IMPL#XXX]** where
**XXX** is an issue number tracking discussion and progress towards implementation.
{{% /note %}}

The Flux language is centered on querying and manipulating time series data.

### Notation
The syntax of the language is specified using [Extended Backus-Naur Form (EBNF)](https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_form):

```js
Production  = production_name "=" [ Expression ] "." .
Expression  = Alternative { "|" Alternative } .
Alternative = Term { Term } .
Term        = production_name | token [ "…" token ] | Group | Option | Repetition .
Group       = "(" Expression ")" .
Option      = "[" Expression "]" .
Repetition  = "{" Expression "}" .
```

Productions are expressions constructed from terms and the following operators, in increasing precedence:

```
|   alternation
()  grouping
[]  option (0 or 1 times)
{}  repetition (0 to n times)
```

Lower-case production names are used to identify lexical tokens.
Non-terminals are in Camel case.
Lexical tokens are enclosed in double quotes (`""`) or back quotes (``).