[[painless-identifiers]]
=== Identifiers

Specify identifiers to <<declaration, declare>>, <<assignment, assign>>, and
<<painless-operators, use>> variables, <<dot-operator, access fields>>, and
<<dot-operator, call methods>>. <<painless-keywords, Keywords>> and
<<painless-types, types>> 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
----
