Formula with each discrete bonded residue or ion shown as a separate moiety. See the CHEMICAL_FORUMULA category description for rules for writing chemical formulae. In addition to the general formulae requirements, the following rules apply: 1. Moieties are separated by commas ','. 2. The order of elements within a moiety follows general rule 5 in the CHEMICAL_FORMULA category description. 3. Parentheses are not used within moieties but may surround a moiety. Parentheses may not be nested. 4. Charges should be placed at the end of the moiety. The charge '+' or '-' may be preceded by a numerical multiplier and should be separated from the last (element symbol + count) by a space. Pre- or post-multipliers may be used for individual moieties.