[OBSOLETE] public int FOO() {...}
or
[Obsolete(\"This is a MESSAGE describing why this method is obsolete\")] public int Foo() {...} NOTE: The O in Obsolete is always capitalized.
[Obsolete] public int Foo() {...}
or
[Obsolete(\"This is a message describing why this method is obsolete\")] public int Foo() {...}
Note: The O in Obsolete is always capitalized.