- C.6.21 (Generic Operator Application). For example: S \rel T. In this case, mixfix and explicit are always true, and the list of instantiating expressions is non-empty (it contains [S,T]).
- C.6.28 (Reference). For example: \arithmos In this case, mixfix and explicit are always false and the list of instantiating expressions is empty. Another example before typechecking is \emptyset. The typechecker transforms \emptyset to a generic instantiation and explicit remains false (see 13.2.3.3).
- C.6.29 (Generic Instantiation). For example: \emptyset[T]. In this case, mixfix is always false and the list of instantiating expressions is non-empty (it contains [T]). The explicit attribute indicates whether the instantiating expressions are explicitly given in the specification (explicit is true) or whether they were inferred by the typechecker (explicit is false).

- C.6.21 (Function Operator Application). For example: S + T. In this case, Mixfix=true, the first (left) expression is the name, (" _ + _ "), (that is, a RefExpr with Mixfix=false!) and the second (right) expression is (S,T).
- C.6.22 (Application). For example: dom R. In this case, Mixfix=false, the first (left) expression is the function, dom, (again, a RefExpr with Mixfix=false) and the second (right) expression is the argument R.

- Membership predicate. In this case, Mixfix=false, the first (left) expression is the element, and the second (right) expression is the set. For example, "n \in S" has left="n" and right="S".
- Equality. In this case, Mixfix=true, the first (left) expression is the left-hand side of the equality, and the second (right) expression is a singleton set containing the right-hand side of the equality. For example: "n = m" has left="n" and right="{m}".
- Other operator application. In this case, Mixfix=true, the first (left) expression is usually a tuple containing the corresponding number of arguments, and the second (right) expression is the operator name. However, for a unary operator, the left expression does not have to be a tuple. For example, "n < m" has left="(n,m)" and right=" _ < _ ", "disjoint s" has left="s" and right="disjoint _ ", and if foo was declared as a unary postfix operator, then "(2,3) foo" would have left= "(2,3)" and right=" _ foo".

A latex markup directive. This is used to represent %%Zchar and %%Zword directives used in latex markup (A.2.3). The Command contains the complete latex command, including the leading backslash, whereas Unicode contains the corresponding unicode representation. The attribute is used to distinguish the kind or type of directive, for instance whether it was a %%Zinchar, which corresponds to type "NONE", or %%Zinword in which case the type is "IN".

Note that there is no unique tranlation back to a latex markup directive in latex since there could be several latex strings representing a unicode string. However, if one does want to translate back into latex markup directives, then directives with a single unicode character should be translated into the various %%Z...char commands and all other directives should be translated into %%Z...word commands (after translating each unicode character into a latex command).