appositives

Otherwise appositives should be set off with commas, when the appositive is critical to the narrative, or parentheses (for when it isn't).

So the source of the confusion is that, in English, non-restrictive appositives typically are indicated with commas, but so are lists of conjuncts.

It can create ambiguity as well as remove it, depending on which terms can be appositives to other terms.

Parentheticals (including non-restrictive appositives) can be set off in English by either commas, em-dashes, or parentheses.

Otherwise, appositives belong with commas (when they’re integral to the sentence) or parentheses (when they’re not).

Em dashes as appositives have the feel of interruption—like this—and are to be used very sparingly.

Em dashes used as appositives carry the feel of interruption—like this—and should be employed sparingly.

I think the author was slightly mixing up the relative clauses and appositives rules with commas.

The way appositives work is that they qualify the preceding subject.

In English appositives aren't considered adjectives, but they do behave similarly.

MS Word automatically converts dashes used for appositives into em-dashes.

Serial commas can also create ambiguity when they resemble appositives[1].