Meta-data
Meta-data are bracketed, arbitrary entries of textual key-value pairs that may be attached to definitions. Meta-data are not unique and may appear more than once, as well as key-value pairs.
[M1]
class A {}
[M1(x="y", z="w")]
class A {}
[M1(y)]
class A {}
Keyless entries are a single identifier or a string literal not accompanied by a key.
Reserved meta-data
Certain meta-data are reserved, such as Event
.