Handling Column 27 of Field 1

12 July 1995

Although it is used in less than a few hundred records, column 27 ["C27"] plays an important bibliographic role for some citations. This column of Field 1 is used for three different, but related, purposes. Upper-case letters in C27 are extensions of the volume number. This usage is described in more detail below. Lower-case letters in C27 are inserted by the editors to provide a unique identifier for an entry when two or more entries would otherwise have identical F1 entries. Finally, the symbols *, +, and ? are occasionally used to indicate that special handling is required to produce an accurate bibliographic citation. A list of all non-blank codes currently used in C27 is given on page 54 of the 1994 User Guide.

A few journals issue ``Supplements,'' or an ``Abstract'' issue, or which carry a modifying letter. These issues are typically paginated separately from the main volume, but carry the same volume number. Thus, for instance, Controlled Clinical Trials issues several (regular) issues per year, but in addition to volume 16, number 3, also issues volume 16, number 3S. The pages in the latter are numbered 1S through 158S. In this particular case, 16(3S) contains abstracts of presentations at the annual meeting of the Society for Clinical Trials, which CIS does not typically index. However, other supplements contain full papers which should be (and are) indexed.

To distinguish the extra issues from similarly-paginated regular issues, the modifying letter is placed in C27 in upper case. Search programs and formatting software should not discard this information when present, as doing so can produce erroneous citations by pointing to the regular issue when a supplement would be correct.

RT