Advertisements on behalf of issuer.  You ask whether a certain advertisement is subject to approval by a principal pursuant to rule G-21, on advertising. You state that an issuer asked the bank to act as its agent in producing the advertisement.  Rule G-21 defines an advertisement as any material (other than listings of offerings) published or designed for use in the public media, or any promotional literature designed for dissemination to the public, including any notice, circular, report, market letter, form letter or reprint or excerpt of the foregoing. The term does not apply to preliminary official statements or official statements, but does apply to abstracts or summaries of official statements, offering circulars and other such similar documents prepared by dealers. Each advertisement subject to the requirements of rule G-21 must be approved in writing by a municipal securities principal or general securities principal prior to first use. The fact that a bank dealer is acting as an agent of an issuer in the production of an advertisement meeting the definition contained in rule G-21 does not relieve a bank from complying with the requirements of the rule.  MSRB interpretation of June 20, 1994.