An essential first step in managing corrosion in any pipeline system is to compile an exhaustive inventory of relevant information into a pipeline register. This chapter outlines necessary information required to capture the full inventory of pipeline systems and their compilation into the pipeline register, and provides a snapshot of steps and elements in this process. The basic pipeline register aims to document a full list of pipelines for which an operating company is responsible for their corrosion management. The existence of physical treatment upstream of the pipeline inlet such as de-aeration, de-carbonation, de-sulphuration, or de-hydration will have a positive impact on system corrosivity as long as these processes are reliably and correctly operated. Similarly, any chemical treatment used for mitigating corrosion can be included in the pipeline register or be readily available elsewhere. Corrosion monitoring data constitutes another essential series of information necessary for corrosion assessments and corrosion reviews.