Rose and McMullin, a regional public accounting firm, has recently accepted a contract to audit On$-$the$-$Spot, Inc., a mobile vending

service that provides vending machines for large events. On$-$the$-$Spot uses a computerized accounting system, portions of which were

developed internally to integrate with a standard financial reporting system that was purchased from a consultant. What type of

documentation will be most useful to Rose and McMullin in determining how the system as a whole is constructed?

Operator documentation

Program documentation

User documentation

Systems documentation