This technical report provides an overview of the datasets and methodology used in the main report, "Investigating the Potential Use of Long-Term School and College Destination Measures. Final Report" (see ED619071). The purpose of the main report is to investigate the potential for using Department for Education's (DfE's) Longitudinal Educational Outcomes (LEO) dataset to historically track the labour market outcomes of young people (up to age 30) who completed their education in the English education system. It also seeks to provide information about the value that schools and colleges can add to young people's destinations. Specifically, the research considers to what extent destination measures can provide information about the 'value-added' by schools and colleges in supporting young people to progress onto high quality destinations. In other words, by 'value added', it focuses on isolating the impact of the institution where they studied their main 16-18 qualification, over and above their prior attainment and wider contextual factors. As this project was of several chosen to pilot opening up the LEO data to third party researchers, in addition to providing an overview of the datasets and methodology used, it also outlines a number of additional recommendations for improving and enhancing the LEO data.