serial number; product key (software)

prologue

(bound form) order; sequence; (bound form) introductory; initial; preface

ordinal number; serial number; sequence number

ordinal number

preface; foreword; preamble; recital (law); also written 敘文|叙文[xu4 wen2]

overture

sequence; order; (literary) to arrange (books) in serial order

prologue; preface; preamble

preface; introductory remarks; preamble; prelude

preface and postscript