From his web page at

Andrew Schulman is the author and editor of several computer-programming books (including Undocumented Windows, Undocumented DOS, and Unauthorized Windows 95) on the internal operation and undocumented features of Microsoft operating systems.

Since 1995 he has worked primarily as a software litigation consultant, providing technical details in legal cases involving copyright, trade secrets, antitrust and, most recently, Internet privacy, providing services such as source-code comparisons (for copyright and patent purposes), inspection of binary code, and assessments of bugs, incompatibilities, error and warning messages.