It's C7+

Placing the + after the 7 makes the + sign less ambiguous. Otherwise, someone might think the + applies to the 7, making a major seventh. I never use plus signs for this reason, but I know many people do use them.

C7#5 will get you the same thing. #5 by itself is a recent addition in BIAB, so it does not show in the list of chord types you see by right-click, Chord Builder, but it works in newer versions of BIAB.



BIAB 2024 Win Audiophile. Software: Studio One 6.5 Pro, Swam horns, Acoustica-7, Notion 6; Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus Studio 192, Presonus Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors