There are two main sections in this document. Section 5 should be consulted by experienced users
who require detailed information on individual PERIOD commands while Section 6 is intended for
inexperienced users who require an introductory recipe detailing the steps that should follow when
searching for periodicities in data.
Please note that PERIOD also has an extensive on-line help facility. This provides information at a level of detail
similar to that found in section 5. However, it also provides a detailed description of the individual prompts,
something which cannot be found in this document.