The package provides a means of labelling diagrams each produced as a Metafont character in a ‘font’ which is produced using the diagramf.mf Metafont package. LaTeX passes data to Metafont (by ordinary LaTeX file-writing mechanisms), and Metafont writes stuff into its log-file, which must then be extracted into a different file so that LaTeX can see it.

The authors are Jeremy Gibbons and Alan Jeffrey.