Missing and invalid data

In some situations, the value specified by your definition cannot be obtained. For example, you specify a value from a field in a record, but the record is too short to contain the field. Alternatively, the record section that should contain the field is absent, or the field is present, but contains non-valid data.

It also happens that the value has been obtained from a field, but you specified an operation on it that cannot be performed. For example, you specified that you want the result of dividing the value from a field A by the value from a field B. If this second value happens to be 0, the requested result cannot be obtained; you cannot divide by 0.