By first standards revision it was mentioned in.
- case
- catch
- class
- const
- debugger
- default
- do
- enum
- export
- extends
- finally
- import
- super
- switch
- throw
- try
- abstract
- boolean
- byte
- char
- double
- final
- float
- goto
- implements
- instanceof
- int
- interface
- long
- native
- package
- private
- protected
- public
- short
- static
- synchronized
- throws
- transient
- volatile
- let
- yield
- await