Z+

Z+ (and the similar Z⁺, in both cases, the letter "Z" and a plus sign) are used sometimes regarding positive ions, i.e., atoms or molecules missing one or more electrons, giving it a positive charge. Ways in which they are used:

• Z+ is used as the superscript of a chemical formula, Z indicating some unspecified positive number, e.g., C^Z+ meaning either C¹⁺ or C²⁺, etc. for ionized carbon that is positively charged, but not specifying the charge amount.
• Z⁺ (i.e., "Z" with "+" as a superscript) uses "Z" to indicate an unspecified element, with Z⁺ representing that element with a positive charge typically meaning a charge of +1 (He⁺, C⁺, etc.).

Z⁺ may sometimes be intended to mean singly ionized, but possibly sometimes that assumption is not intended (i.e., C²⁺, O³⁺, etc.). However, the electrical charge can specified explicitly, e.g., Z⁺⁺ or Z²⁺.