Sherman reminds us, then, in early modern England, 'marking' one's 'words' was a physical act performed by a reader upon a book as well as one of mental concentration, and could even mean 'writing a glossarial
note or commentary', as well as simply underlining or otherwise indicating material of interest.
Although this edition supersedes in almost every way the version of the essay as published previously by Christopher Tolkien, there is one unfortunate loss: Tolkien's "glossarial
commentary" accompanying the poem, "Oilima Markirya." This is a series of Qenya words and English glosses keyed to the poem by line number (see Monsters 222-3 and PE 16 75).
Stephen Booth's helpful glossarial
explanation of Sonnet 15 can help further strengthen the point:
(7) James Boswell, ed., The Plays and Poems of William Shakespeare, with the corrections and illustrations of various commentators, comprehending a life of the poet and an enlarged history of the stage, by the late Edmond Malone, with a new glossarial
index, 3rd variorum ed.