pem

var (
	//: register the singleton and expose it as a typed package var.
	Codec codec.Codec = codec.Register(&pemCodec{extensions: extensions})
)

Package-level state: the codec singleton, built with its hoisted extension table — the initialiser names the table, which is what orders it before Register reads it (see core/data/codec.Register) —, the cached promotion fast-path markers, and the Marshal-buffer pool.