Mdtryhht

(NOT A DUPLICATE — Go to the end for research.)

Are there situations in which punctuation (e.g., comma (,), period (.), exclamation point (!), question mark (?), colon (:), and semicolon (;)) may grammatically appear immediately before or after an em dash (—)?

Example Citation:

Dare not rob dear Ozzy, our still-reigning Prince of Darkness—Long live the Prince!—, of his honorificabilitudinitatibus with such unseemly floccinaucinihilipilification.

-or-

Dare not rob dear Ozzy, our still-reigning Prince of Darkness—Long live the Prince!—of his honorificabilitudinitatibus with such unseemly floccinaucinihilipilification.

In my estimation, which doesn't concede omitting it would necessarily be ungrammatical, the punctuation after the em dash in the first example does belong there. That's because without it, it doesn't, in my view, clearly link the ensuing "of" to the aforementioned "Ozzy" as it should; without it, it becomes unclear what "of" attaches to, kind of like if you left a parenthesis off in a mathematical equation containing multiple sets of nesting parentheses. But I'm having a difficult time either solidly justifying or solidly debunking my estimation grammatically. Thus, I'm coming to you all for help.

Here are some research examples of why I think it may be allowable:

Beauty is truth, truth beauty, —that is all ye know on earth, and all ye need to know.

-John Keats in "Ode to a Grecian Urn"

-and-

...turn awry and lose the name of action. — Soft you now, the fair Ophelia! — Nymph, in thy orisons be all my sins remembered."

-William Shakespeare in Hamlet

Now, I realize these references are old and grammar changes, so what was grammatical then may not be grammatical now. I am hard-pressed, however, to find anything that specifically addresses the grammaticality of this issue, i.e., if the rule has changed, specifically when and where and how and why and by whom?

I understand some style guides may weigh in on this, which weigh-ins I would appreciate—if only for the sake of consensus-building in lieu of any actual grammar source providing a definitive answer—since I don't have paid subscriptions to any of the major style guides and some of you might. That said, I'm not actually looking for answers as to style but answers as to grammar, for many style guides prescriptively bar punctuation that nevertheless remains grammatical (e.g., the Oxford comma).

Brass tacks: Is the comma after the em dash in the example citation I provided above at the top grammatical or not? Is Keats' comma grammatical? Is Shakespeare's period? Is Shakespeare's exclamation point?

Please source your answer if you can, but I do recognize that you yourselves are sources and so won't turn my nose at a predominance of your expert opinions coming in one way or the other.

RESEARCH - NOT A DUPLICATE QUESTION

I did research this question and found this to be the most closely related question on this website:

How is punctuation used after dashes?

This is NOT A DUPLICATE of that, however. My question also asks about punctuation before em dashes and expressly seeks answers of grammar, not style. The asker doesn't explicate either way, grammar or style, but the asker implies only looking for a style answer as the asker selected an answer before any answers of grammar are given, only recommendations about style.

To be clear, no answers of grammar are posted to this other question, meaning the two answers to it fail to answer my question, as follows:

• The selected answer doesn't even answer the asker's question, much
  less mine, because it cheats the asker by instead recommending
  sidestepping the issue by rephrasing, which isn't a bona fide
  answer, like what if I'm not the writer and am tasked to grade a
  paper as it is written, not as it could've been written?


• The only other answer, the answer not selected, is actually somewhat
  more helpful, but it doesn't clarify it's an answer of grammar, which is
  what I'm seeking, but only an answer of style, what The Chicago
  Manual of Style prescribes. I'm not operating under that style guide
  or any style guide, though. Grammar and style are two different things,
  and I'm looking for an answer of grammar, not style.

Another question that came up in my research that is also NOT A DUPLICATE is the following:

em dash followed by a comma

The above question is actually marked as a duplicate of the one listed further above, but it does have an answer, so I did look into it even though the question itself likewise does not address my complete question, neither specifically nor generally. The one answer also falls short by providing:

• an answer whose only source links to a style guide—not a widely
  accepted style guide like MLA or APA, either, but Menlo College's
  style guide, some small college in California—rather than any grammar
  textbook, grammar source, or any statement it's grammar,
  not style, like by using words like "grammatically required,"
  particularly in lieu of words like "recommended";


• an answer whose only source fails to elucidate this issue
  expressly—or even implicitly in the handful of examples it gives; and


• an answer that itself fails to indicate whether or not a comma can
  properly follow an em dash, which is the poster's actual question and
  likely why that only answer provided has been voted down more than
  up, having a -1 score.

So that there's no confusion, regardless of the poor quality of the answer given to this other question, my question has a far broader scope than the question itself and so is not a duplicate of it.

Also NOT A DUPLICATE are all the various other questions I researched with possibly related titles, including but not limited to Combining m-dash and comma, Mixing em-dash and comma, Long dashes between sentences, and Punctuation following em dash and speech mark.