2. Conformance
A conforming implementation of ECMAScript must provide and support
all the types, values, objects, properties, functions, and program
syntax and semantics described in this specification.
A conforming implementation of this International standard shall
interpret characters in conformance with the Unicode Standard,
Version 2.1 or later, and ISO/IEC 10646-1 with either UCS-2 or
UTF-16 as the adopted encoding form, implementation level 3. If the
adopted ISO/IEC 10646-1 subset is not otherwise specified, it is
presumed to be the BMP subset, collection 300. If the adopted
encoding form is not otherwise specified, it presumed to be the
UTF-16 encoding form.
A conforming implementation of ECMAScript is permitted to
provide additional types, values, objects, properties, and
functions beyond those described in this specification. In
particular, a conforming implementation of ECMAScript is permitted
to provide properties not described in this specification, and
values for those properties, for objects that are described in this
specification.
A conforming implementation of ECMAScript is permitted to
support program and regular expression syntax not described in this
specification. In particular, a conforming implementation of
ECMAScript is permitted to support program syntax that makes use of
the "future reserved words" listed in 7.5.3 of this
specification.
