An information letter provides general statements of well-defined law without applying them to a specific set of facts. They are furnished by the IRS National Office in response to requests for general information by taxpayers, by congress-persons on behalf of constituents, or by congress-persons on their own behalf. An information letter is advisory only and has no binding effect on the Service. An information letter may be issued if the taxpayer's inquiry indicates a need for general information or if the taxpayer's request does not meet the requirements for a letter ruling or a determination letter, and the Service thinks general information will help the taxpayer." (Internal Revenue Manual, § 32.3.1.1)
Westlaw has IRS information letters from 2000-present.