CUSIP Numbers for Callable Multi-Series GOs: Rule G-34
Rule G-34 requires underwriters and dealers participating in the placement of a new issue of municipal securities to ensure that an application is made for CUSIP numbers for the new issue. The CUSIP Service Bureau assigns CUSIP numbers to reflect the differences in securities that are relevant to trading and investment decisions. In addition, Board rules G-12 and G-15 require that CUSIP numbers appear on confirmations of transactions and that the securities delivered on those transactions match the CUSIP numbers appearing on the confirmations.
Recently, certain questions have arisen about the proper method for assignment of CUSIP numbers to certain general obligation securities that have been issued in multiple series. In these issues, the issuer uses the proceeds from each series to fund a separate project, but the project itself offers bondholders no additional security for payment beyond that provided by the full faith and credit of the issuer. Securities within multiple series may be identical with respect to dated date, maturity, security and source of payment. However, an individual series may be called, in whole or part, at the option of the issuer, based on the series designation. In addition, the securities are subject to certain mandatory redemption features, which are exercisable by series and which are dependent upon the status of the project funded by the series.
Underwriters have encountered confusion as to whether each series within these issues should be assigned separate CUSIP numbers or whether the CUSIP number assignment for the issues should ignore the series designation. The Board wishes to clarify that, because of the possibility that the securities will be subject to early redemption by series designation, separate CUSIP numbers for each series are required.
The Board previously has indicated that a designation of multiple "purposes" for general obligation debt does not require separate CUSIP numbers for each purpose if the securities otherwise are identical. Accordingly, there are a number of outstanding multi-series general obligation issues which are assigned one CUSIP number for each maturity and which are traded, cleared, and settled without regard to series designation. While the Board does not wish to change this general rule, it believes that separate CUSIP number assignment is required for those multi-series issues which can be called by series. The Board notes that the probability of a partial or "in-whole" redemption of a series has the potential to become a significant factor to investors and that it therefore is necessary to preserve distinctions among the various series when trading, clearing and settling these securities.
The Board has consulted with the CUSIP Service Bureau in this matter and the Service Bureau has agreed to assign separate CUSIP numbers to multi-series general obligation issues which can be called by series. Dealers serving as underwriters for these issues therefore should not request the Service Bureau to ignore the series designation when assigning numbers to these issues.
The rule applies to all issues eligible for CUSIP number assignment. This includes nearly all new issue securities over three months in maturity.
 CUSIP numbers are assigned to municipal issues by their issuer title, dated date, interest rate, and maturity date. Municipal securities which are identical as to these four elements are assigned different numbers if there is a further distinction between the securities involving any of the following:
(1) the call features (i.e., whether or not securities are callable, date or terms of call feature, etc.);
(2) any limitation of the pledge on a general obligation bond (e.g., limited tax versus full faith and credit);
(3) any distinction in the secondary security or the source of payment of a revenue bond;
(4) the identity of any entity, besides the issuer, obligated on the debt service of the securities (e.g., two pollution control revenue bonds secured by different corporate obligors); and
(5) any distinction in the secondary security or the source of payment of a general obligation bond.
 Certain exceptions to these rules exist for securities which have not been assigned CUSIP numbers and instances in which the CUSIP number on a confirmation and the CUSIP number assigned to securities differ only because of a transposition or transcription error.
 See MSRB Reports Vol. 2, No. 1, (January 1982), p. 3. Of course, if specific portions of a general obligation issue are additionally backed by the revenues from various issuer activity or proceeds from various projects (so-called "double-barrelled" issues), separate CUSIP numbers are required to reflect these distinctions.