The Label field can be used for many purposes, such as special in-text citations or reprint numbers.
Some citation styles require that citations include only part of the author’s name, such as [SMIT 90]. EndNote cannot create this citation for you, but if you type " SMIT 90" into the Label field and use the Label field in your style’s citation template, EndNote will insert the Label field into the citation.
If you do not need the Label field for citation purposes, it can be used as an additional field for categorizing references or storing reprint numbers. (Do not use EndNote’s record numbers to number reprints because these numbers change when references are moved to different libraries. EndNote’s record numbers cannot be assigned or changed by the user.)