Q. My publisher prefers that AD come before the year (as in “AD 99”), but would the same rule apply to centuries? That is, should it be “first century AD” or “AD first century”?

Q. Does Chicago prefer “COVID-19” or “Covid-19”?

Q. Isn’t it redundant to have an “MBA in business administration”? I thought it was a mistake at first, but a lot of people use this—and perhaps it really is the degree name—but it just seems weird . . . “master of business administration in business administration”?

Q. Once and for all: to abbreviate “postscript” at the end of correspondence, is it best to write PS or P.S.? The glossary in CMOS advises no periods, but several examples in the Q&A use them, like this one. Help!

Q. I hate defining acronyms in the first paragraph of a paper because they impede flow. Therefore, is it acceptable to repeat the whole phrase, in this case, greenhouse gases, in the second use, and then define it there as (GHG)?

Q. I’m working on some writing that mentions “SQL servers.” I’m wondering whether I should go with “this data is stored on an SQL server” or “a SQL server.” I happen to be aware that “SQL” is usually pronounced “sequel,” which would lead me to write “a SQL server.” However, I worry that anyone unfamiliar with the term would assume each letter is pronounced individually—and it is very likely that the language I’m working with will be seen by many who are unfamiliar with SQL. What do you recommend?

Q. Is Q&A an acronym or an abbreviation? When using Q&A in, say, a training in PowerPoint, do you need to write out “Questions and Answers” the first time, like you would in an acronym, or does it stand on its own as Q&A?

Q. Hi, can you tell me what “pl.” stands for in “vol. 5 (1822), pl. 57”? Thanks!

Q. I’m wondering about omitting the periods for US Department of Energy. On its site, it’s U.S. Do we follow the department’s preference or Chicago style?

Q. What is the proper way to write Dr. Tom Smith Jr., M.D.?