We are all familiar with digital object identifiers (DOIs) provided by CrossRef to identify (and link to) journal articles. Some of us are familiar with the DOIs issued by DataCite to link to datasets. But most of us don’t know that CrossRef is also providing component DOIs that can provide persistent links to a particular table or figure in a paper. The PLoS journals use component DOIs, for example for this figure:
Correlations between 37 measures mapped onto first two principal components (cumulative variance = 83.4%) of PCA. doi:10.1371/journal.pone.0006022.g002. From Bollen J, Van de Sompel H, Hagberg A, Chute R (2009) A Principal Component Analysis of 39 Scientific Impact Measures. PLoS ONE 4(6): e6022. doi:10.1371/journal.pone.0006022
Linking to component DOIs is straightforward, table 1 of the paper above is 10.1371/journal.pone.0006022.t001. Unfortunately only about 300,000 of the more than 40 million CrossRef DOIs are compontent DOIs. There are many good reasons to use a direct (and persistent) link to a specific part of a scholarly journal article. And this becomes an even more important issue once DOIs for datasets are more commonly cited.