On 2018-02-18 14:33, Wolfgang Schuster wrote:

It does not matter how many fonts support both (LM does, and Libertine). One feature of a BibTeX file is reusability for many documents, and when the file is created you do not know what will be the default emphasis of the document. By explicitly coding \it, you are assured that the italic face will be attempted. If it is not available, there should be an error message, and you can then have a discussion with your editor. The claim of the new bibliography subsystem is that it will implement APA strictly, and that calls for italic.

I understand as well that \em allows switching (reverse emphasis as noted above). It also provides some italic correction. I am asking about the appropriate use of the two variations of \em: \emph (which is a grouped command \em) and \emphasized (defined as \bgroup\em\let\nexttoken). I understand and make use of grouped commands -- they are largely syntactic sugar, but I like sugar. I am less certain of the purpose of \emphasized, how it works, and why it might be useful. I do not recall seeing a command definition with a bgroup and no egroup before.