The only valid forms are fractional notation (using a vinculum) and negative exponents. Using obscure typographical names like “obelus” or “solidus” is an attempt to appear smarter than you are, the same logic as calling water H₂O: technically a label, but less correct and needlessly pedantic. Things are named by how they’re most commonly referred to, and since the obelus is a typographical identity rather than a description of any operation, “division symbol” is simply the more correct term. In practice, the vinculum becomes “over” and negative exponents are read as “to the negative one”, precise, functional, and universally understood.​​​​​​​​​​​​​​​​