$STRING NONMEMBER                       # a free function (the default)
$STRING MEMBER OF app::Reporter         # const member of your class
$ERROR NONCONST MEMBER OF Reporter
$STRING MEMBER AS text                  # member of the streamable class

CONST / NONCONST are optional; the default is CONST. After MEMBER comes OF with a qualified name or AS with a name.

app.msg:1:15: error: expected OF or AS after MEMBER
app.msg:1:14: error: expected MEMBER after CONST

Semantics: Reference › Member functions.