I found somebody used the term “punctuation K23” to find my site. I can only guess that because in A Clear and Feathered Danger they’ll find “Tower K-23.” I’m well aware of that and did it on purpose. K-23 refers to Tower K-23, where my protagonists have their office. K23 refers to the detective agency itself and the series title. In universe, this makes sense, because there are other private detectives in Tower K-23 and naming your agency “The K-23 Detective Agency” pretends they don’t exist. So Alfonso removed the hyphen.
Why K23 as series name in general, it rolls of the tongue and if this ever becomes a TV show(in my dreams anyway), “previously on K23…” sounds cool to me in general.