In ProAdmin, an array is a date-dependent set of values which may be codes, numbers, or dates. The following are arrays that are typically encountered and used in ProAdmin:

• Array fields
• #THIS
• #DATE
• The results of a Benefit Definition, Benefit Formula Component, and Accrual Basis Component (available in higher level expressions, such as Accrual Definitions, Subformulas, Benefit Expressions)
• Some temporary variables in service & salary transformation expressions, and in Accrual Definition, Subformula, and Benefit Formula expressions. In this case of temporary values, the effective date for each value is #DATE and the temporary variable holds the values of the array.  Here are some examples of temporary variables definitions that do and do not create arrays:

A:= #ENDMTH #DATE & ; array
B:= #THIS >= 1000 & ; array
C:= SALARY  & ; array (salary is a start/stop array field*) 

D:= 1       & ; scalar (i.e., a single value)
E:= DOB     & ; scalar (i.e., a single value)

*You should also see assignment using array fields in transformation expressions and assignment using array fields in data default expressions.

Expressions are any series of math operators (+, -, *, /, **), ProAdmin built-in operators and user-defined components that cause ProAdmin to compute a result.  Press the F1 key, while the cursor is within the expression box, to see a list of all fields and operators that may be used to construct the expression.