There is a wealth of information available from the IRS that is not generally made available to the public.  Most of this information can be obtained by asking.  This information includes files the IRS assembles about a taxpayer, and various training manuals used by the IRS to train its employees.  In addition to training given to its employees, the IRS, like most professional organizations, conducts continuing education on an annual basis for its various divisions.  Most of the training manuals and annual training materials are available to the practitioner pursuant to the Freedom of Information Act (FOIA).