docs-v2/content/v2.0/reference/flux/language/_index.md

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---
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 query language
weight: 102
---
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 (``).