Peter Schaffter suggested a couple of years ago:

... I proposed %e as a candidate for the edition field
because it's been around long enough in mom that it makes sense for
other macro packages to follow suit.  Plus it has the advantage of
being a meaningful [mnemonic].

Mom implements five additional fields
for Internet sources as required by MLA:

  %s site name
  %c content (e.g. Web, Email, Blog...).
  %o organization, group, or sponsor or the site
  %a access date
  %u URL

Methinks, in 2021, that the other groff macro packages should catch
up with this newfangled Internet thingy.