Parameters 4 through 6 are the key identifiers. They all have the same format. Parameter 4 is the first key to sort on, parameter 5 is the second, parameter 6 is the third.
For each key, you must specify the key type (number, date, International or ASCII), the field number (based on the value given for parameter 2), the sort direction (ascending or descending) and the chunk within the field (word, item or character).
The information for each key can be in any order within the parameter. Only the first letter is significant and it can be in either upper or lower case.