The World List was designed to standardize journal abbreviations to ensure each one indicates only one specific periodical. According to the Preface to the Second Edition , researchers were urged to use these exact codes to avoid confusion among more than cataloged.
Alternatively, it may refer to the series. Context of the World List 45imp4
publications (specifically technical communications or reports). The World List was designed to standardize journal
Could you clarify if you are looking for the indexed under this code, or a description of the periodical itself? 45imp4