Appraisal Standards rules 6.2.23 and 6.2.24 impose requirements to analyze any agreement for sale, option or listing of the property (6.2.23) and analyze any prior sales of the property (6.6.24). Beyond the necessity of meeting compliance requirements, following these rules can be of considerable assistance and directly beneficial to the appraisal process. In some circumstances, such research and obtaining the necessary information can be onerous and, in some jurisdictions, only limited historic data is available. But as always, an extraordinary limiting condition may be necessary in the event that adequate compliance with any Standards rule is not possible. Although most appraisal assignments are point-in-time valuations, knowledge of the entire recent history of the property is fundamental to a sound analysis.