Italics don't have +lnum

[alerque]

As can be seen in samples from #20, the Italic style doesn't seem to have +lnum.

[thlinard]

More generally, the features and classes aren't synchronized between Roman and Italic.

For example, Italic has a case feature (which could be extended, since there are 3 .case glyphs) that Roman doesn't have. The Roman has a lnum class with all the .lf glyphs: by duplicating it, the dnom_frac_numr_ordn_sinf_subs_sups class of the Italic could be renamed to dnom_frac_lnum_numr_ordn_sinf_subs_sups, and the lnum feature of the Roman could be imported directly.