The Thomson Reuters Insider Filing Data Files are designed to capture all insider activity as reported on SEC forms 3, 4, 5, and 144. In addition, Thomson Reuters adds value by making systematic interpretations on the accuracy of as-reported data and inserting “cleansed” fields for comparison. A cleanse code is included to denote the overall level of confidence in each record.
Corporate insiders are defined broadly to include those that have "access to non-public, material, insider information" and these insiders are required to file SEC form 3, 4, and 5 when they trade in their companies stock. Many times the actual insider files his or her own forms and sometimes the company's CFO or general counsel or a private attorney files on behalf of the insider. Each insider must sign the forms themselves, no matter who does the actual filing.
The table Datasets List and Sample Programs under Support provides some Insiders sample programs that may help you to get started.