As far as possible, entries follow the relevant authority record in the Library of Congress. The place of publication is always London, unless otherwise stated under the entry for the publisher.
Headwords — Some ballad operas were mainpieces which were later cut down to be afterpieces. Because the abridged version could differ radically from the original, mainpiece and afterpiece ballad operas with the same title are catalogued separately, each receiving a headword. All subsequent afterpiece versions are catalogued under the first afterpiece headword. Occasionally, the afterpiece was titled differently than its original mainpiece; the data field ‘Dramatic Source’ shows the link between the afterpiece and its mainpiece. Similarly, a few ballad operas that appeared only in print were re-issued under a different title. These works receive their own headword, and the data field ‘Dramatic Source’ shows their source.
Advertisements — Advertisements are taken from the 17th-18th Century Burney Collection Newspapers Digitisation Project. Only the earliest advertisement is transcribed. Advertisements are transcribed in full, without reproducing italics; an ellipsis indicates where words were missing in the original, and [?] indicates a provisional completion of missing letters or words. Due to resource constraints, the only newspaper announcements by booksellers/publishers transcribed in this catalogue are those for published-only works.
Performed Only/Published Only — This classification reflects our current knowledge, but may be overturned by future findings, such as the discovery of an edition not listed on ESTC, or an advertisement not yet found.
Dramatic Source — Many ballad operas were based on earlier or contemporary events, accounts, or stage works. This field roughly indicates the source of the ballad opera's plot. Due to resource constraints, this information is still incomplete.
English Short Title Catalogue Number/Date of Publication — We cite what we believe is the first edition of each work. Apart from published-only works, we have not had the resources to verify through newspaper advertisements that the ESTC volume cited is, in fact, the first edition.
Eighteenth-Century Collections Online — We indicate only if a ballad opera edition is contained in ECCO, but do not specify by ECCO number an edition of the ballad opera to be viewed. ECCO captures many editions worth viewing, although it does not necessarily reproduce the first edition.
Uniform Titles for Airs — Airs are assigned uniform titles (UT) to allow the user to identify tunes which are the same yet carry different titles. The source of each uniform title - usually the title under which the tune was most commonly known - is given under 'UT sources'.
Air numbers — Airs are assigned an Arabic number signifying the order of their appearance in the first edition. The 'Published air number' reproduces the air's number as it appeared in the first edition, where a Roman numeral was usually used. Due to publishers' errors in numbering airs, the number assigned to an air in this catalogue may differ from the air's number in the first edition.