ConstAn exported function that is also an S3 class this package OWNS: it is a same-named constructor for a class the package registers at least one S3 method for (see LibraryExports.s3Classes, derived from this bit by deriveLibraryExports).
Set on the name of an S4 class this package OWNS: it exports the class via its NAMESPACE exportClasses()
(see LibraryExports.s4Classes, derived from this bit by deriveLibraryExports).
function-level boolean properties, packed into SigFn's bitfield