When utilizing TitleLeaf, the term Set should not be confused with the term Series. TitleLeaf follows closely the ONIX for Books standard. To paraphrase their definitions, a Set is a salable product, composed of a fixed number of sub-products. A Series is not a salable product; it is a grouping for marketing purposes of an indefinite number of products published over an indefinite period of time.
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For an exact definition, please consult the following excerpts from ONIX for Books, Release 2.1, Revision 03:
PR.5 Series
A “series” means an indefinite number of products, published over an indefinite time period, and grouped together under a series title, primarily for marketing purposes. A series does not have an EAN-13 number, ISBN or UPC, and it is not traded as a single item, although it may be possible to place a standing order for successive items in the series to be supplied automatically.
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