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These cataloging guidelines are written as an accompaniment to the Plaine & Easie Code (PAEC) specification. In previous editions of the specifications, the formal description of the code, and the guidelines for its interpretation, were given as a single document. Although convenient as a reference, it also posed significant challenges for the interpretation of what was actually required, and what was recommended. In the new edition of the PAEC, the specification document provides a formal description of a valid PAEC encoding, while this document will provide recommendations on the application of the code to incipit capture.
The thematic index derives its superiority over non-thematic lists be cause it can not only arrange a body of music in a systematic order, but it provides, at the same time, positive identification in a minimum of space and symbols. It does so by the use of the "incipit," or musical citation of the opening notes. For most music, an incipit of no more than a dozen pitches is required. When rhythmic values accompany the pitches, the incipit's "uniqueness quotient" is astonishingly high.
A musical work, printed or manuscript, may be identified by composer, title, opus number, key, instrumentation, movement headings, first line of text, date, publisher, dedicatee, plate number, etc. No one of these, indeed no combination of these, can provide as certain an identification as an incipit. For example, an anonymous 15th-century Latin motet may also appear as a French chanson entitled "L'amant douloureux." A composer may write a dozen trio sonatas in D major, three of them with the same tempo sequence. A concert aria found in a library in Vienna, in the key of F, may turn up in Prague in the key of G, and with added horn parts. Two printings of a set of quartets may be given different plate numbers by the same publisher. Two publications of the same opera, in different cities, may bear different titles, and dedications to different patrons. Finally, a set of six symphonies may be published in Amsterdam with one opus number, in Offenbach with another, and in London within a series of Periodical Overtures without any at all, and under another composer's name.
By contrast, the presence of the incipit avoids confusion. Identification is certain. Even transposed works can be readily identified in properly organized incipit files. In dealing with anonymi and with works of disputed authorship, the incipit becomes indispensable-as a catalog without them will readily demonstrate. In short, the collection, classification, transposition, and lexicographical ordering of the incipits into thematic catalogs have enabled scholars to solve a myriad of otherwise insoluble problems, and have provided musicians, librarians, students, biographers, and program annotators with an invaluable reference tool.
The cataloging of musical incipits in RISM is primarily intended for the purposes of identification and disambiguation, where all other bibliographic means of doing so are not sufficient to uniquely identify a musical piece.
The most important component of incipit cataloging is the capture of identifiable musical material. This will, in most cases, be the opening measures of a piece. It may, occasionally, be the entrance of a melodic instrument when the opening of the piece starts with otherwise ambiguous accompaniment, such as a ground bass. In rare instances, it may be the entrance of a theme that is many measures in.
In all cases, the encoder of the incipit must keep in mind the primary motivations of identification and disambiguation when choosing the musical content to capture as the incipit. It does not serve the users of the catalog to encode a unique part of a musical work when all other instances of the incipit in the catalog identify the opening measures. The uniqueness of the cataloging simply means that the incipit will not group with like, and it will thus be "lost" in the larger catalog.
The capture of melodic and rhythmic qualities is of primary importance. Considerations of visual appearance, phrasing, polyphony, or other special indications are of secondary importance, or should be ignored altogether, when capturing incipits. While it may seem important to capture for any single given source, it can also pose significant challenges to positive identification or disambiguation when compared to all other sources. Other means of capture, such as analytical notes fields, may be a more suitable mechanism for accurately describing these features.
From the beginning, the PAEC was purpose-built for the capture of identifying incipits. It could be written by hand, or typed on a standard mechanical typewriter. Unlike other codes, the goal of the PAEC was to be simple. Indeed, the first version of the PAEC, issued in 1964, was subsequently simplified in 1965, to "make the code more usable on an international basis." (Brook, Fontes, 1965). The current PAEC specification is based primarily on this simplified version.
In the intervening years since the introduction of the PAEC, a number of changes and additional features have been introduced. In some cases these additions have significantly improved the coding scheme; in other cases the additions have ultimately distracted from the central purpose of the PAEC when put into practice. The reasons for these changes are not always known. They may have been in response to a specific need, or they may have been added as a "nice-to-have" without an identified use case. Whatever the reason, they have been available and widely adopted and standardized, making it difficult to introduce retrospective changes to the coding system to address problems and clarify ambiguities. With no clear versioning scheme in place, the previous version is now no longer updated, and is now known as "Version 1".
The new version, Version 2, contains several backwards-incompatible changes from Version 1. It is not the case that incipits in Version 1 need to be "upgraded," nor is it a problem to have software or other standards support PAEC Version 1. It is simply a way to differentiate the two versions. In most cases, unless the version of the incipit is plainly stated as being Version 2, it should be assumed that it is supposed to conform to Version 1 of the specification.
The goals of the effort behind Version 2 were to clarify ambiguities in the previous specification, and to make the PAEC more suitable for machine processing of incipits. Since the previous version was developed before the World Wide Web, and even before there was software available to render the code into a graphical representation, several parts of the specification existed that made it difficult to unambiguously and reliably process the data into the notation it was intended to represent.
Version 2 of the specification is written to make the requirements of the encoding system clear, to help software developers to build applications that can process the data in a uniform way. The requirements are given using [RFC2119], which provide keywords, such as "MUST" and "MAY", to indicate required or optional features, respectively. Most of the sections in the specification have also been expanded to include an actual description of the code, as well as illustrative examples.
This version of the code is maintained by the International Association of Music Libraries, Archives and Documentation Centres (IAML) and the Répertoire International des Sources Musicales (RISM) for use as an exchange format in the library environment.
Music incipits help identify works and facilitate the comparison of historical musical sources.
Which music incipits to enter depends on the kind of music. Best practice for instrumental music is to enter incipits for the violin or the highest part. For vocal music, enter the highest voice plus the first violin or the highest instrumental part.
The incipit should be neither too long nor too short, and make as much musical sense as possible. It should contain at least 3 bars or 10 non-repeated notes.
If the music is written for a transposing instrument, notate the incipit at sounding pitch.
Notation abbreviations, such as tremolo, slash, etc., must be written out in full using the actual notation.