There is a [grammar specification](./grammar.w3c-ebnf) about the query syntax,

which may be helpful if you're implementing a parser or something else.

NonSpaceChar ::= [#x21-#xD7FF] | [#xE000-#xFFFD]

Digit ::= [0-9]

Space ::= ' ' | '\t'

Numeric ::= (Digit* '.')? Digit+

BrowserName ::= 'ie'

| 'edge'

| 'firefox'

| 'chrome'

| 'safari'

| 'opera'

| 'ios_saf'

| 'op_mini'

| 'android'

| 'bb'

| 'op_mob'

| 'and_chr'

| 'and_ff'

| 'ie_mob'

| 'and_uc'

| 'samsung'

| 'and_qq'

| 'baidu'

| 'kaios'

| 'fx'

| 'ff'

| 'ios'

| 'explorer'

| 'blackberry'

| 'explorermobile'

| 'operamini'

| 'operamobile'

| 'chromeandroid'

| 'firefoxandroid'

| 'ucandroid'

| 'qqandroid'

CompareOperator ::= ('>' | '<') '='?

VersionKeyword ::= 'version' 's'?

LastBrowsers ::= 'last' Space+ Digit+ Space+ (BrowserName Space+)? ('major' Space+)? VersionKeyword

LastElectron ::= 'last' Space+ Digit+ Space+ 'electron' Space+ ('major' Space+)? VersionKeyword

Unreleased ::= 'unreleased' Space+ ((BrowserName | 'electron') Space+)? VersionKeyword

Years ::= 'last' Space+ Numeric Space+ 'year' 's'?

Since ::= 'since' Space Digit+ ('-' Digit+ ('-' Digit+)?)?

Region ::= ('alt-' [a-z][a-z] | [A-Z][A-Z])

MyStats ::= 'my' Space+ 'stats'

CustomStats ::= NonSpaceChar+ Space+ 'stats'

Percentage ::= CompareOperator Space* Numeric '%' (Space+ 'in' Space+ (MyStats | CustomStats | Region))?

Cover ::= 'cover' Space+ Numeric '%' (Space+ 'in' Space+ (MyStats | Region))?

FeatureSupport ::= 'supports' Space+ ([a-z0-9] | '-')+

Version ::= (Digit | '.')+

BoundedRange ::= Version Space* '-' Space* Version

UnboundedRange ::= CompareOperator Space* Version

Electron ::= 'electron' Space+ (BoundedRange | UnboundedRange | Version)

Node ::= 'node' Space+ (BoundedRange | UnboundedRange | Version)

Browser ::= BrowserName Space+ (BoundedRange | UnboundedRange | Version | 'tp')

FirefoxESR ::= ('firefox' | 'fx' | 'ff') Space+ 'esr'

OperaMini ::= ('operamini' | 'op_mini') Space+ 'all'

CurrentNode ::= 'current' Space+ 'node'

MaintainedNode ::= 'maintained' Space+ 'node' Space+ 'versions'

Phantom ::= 'phantomjs' Space+ ('1.9' | '2.1')

BrowserslistConfig ::= 'browserslist config'

Extending ::= 'extends' Space NonSpaceChar+

Defaults ::= 'defaults'

Dead ::= 'dead'

QueryAtom ::= LastBrowsers

| LastElectron

| Unreleased

| Years

| Since

| Percentage

| Cover

| FeatureSupport

| Electron

| Node

| Browser

| FirefoxESR

| OperaMini

| CurrentNode

| MaintainedNode

| Phantom

| BrowserslistConfig

| Extending

| Defaults

| Dead

SingleQuery ::= ('not' Space)? QueryAtom

OrOperator ::= Space+ 'or' Space+ | Space* ',' Space*

AndOperator ::= Space+ 'and' Space+

BrowserslistQuery ::= QueryAtom ((OrOperator | AndOperator) SingleQuery)*

Root ::= BrowserslistQuery