Over the years, many different particle and electromagnetic signatures have been invoked to identify the onset of what is called a substorm. In this paper I shall first clarify what is generally meant by the term substorm onset, and I shall show that some disturbances identified as substorm onsets should be treated with care. I shall review the substorm in terms of its two recognized characteristic components: directly driven and storage/release. I shall then discuss the importance of pseudobreakups in deciding what constitutes a legitimate substorm onset and, in doing so, will illustrate the subjective nature of present substorm onset identification techniques. I shall stress that substorm-like disturbances can take place both near the equatorward edge of the midnight sector oval (mapping to the near-Earth magnetotail inside ~-12 RE) and near the poleward edge of the evening sector oval (mapping to regions much farther downtail). I shall present case studies that illustrate that some poleward edge disturbances have magnetic and auroral signatures that may be incorrectly interpreted as legitimate expansive phase onsets. On the basis of this study, I suggest that what may appear to be a lengthy series of closely spaced expansive phases may, in fact, be a single expansive phase followed by an arbitrarily long period of poleward border activity.