There are two files in a study: Trial Master File and Site Master File (also known as Investigator Site File). The SMF/ISF is in control of the site and the sponsor does not have access to it. However, there are documents that should be both in the SMF and TMF/ISF. Reconciliation is a process that allows you to verify that the documents that are stored in the TMF are also found in the SMF/ISF.