[[painless-identifiers]]
=== Identifiers

Use an identifier as a named token to specify a
<<painless-variables, variable>>, <<painless-types, type>>,
<<dot-operator, field>>, <<dot-operator, method>>, or function.
<<painless-keywords, Keywords>> cannot be used as identifiers.

*Grammar*
[source,ANTLR4]
----
ID: [_a-zA-Z] [_a-zA-Z-0-9]*;
----

*Examples*

* Variations of identifiers.
+
[source,Painless]
----
a
Z
id
list
list0
MAP25
_map25
Map_25
----