lookupString(one key column), given a key column, constructs the row source key, looks up the row source entry, and returns the string value of resultColumn from the row source.
lookupString(String rowsourceName, String keyColumn1, String resultColumn)lookupString(two key columns) looks up a row source with two key-columns for the value resultColumn
lookup(String rowsourceName, String keyColumn1, String keyColumn2, String resultColumn)lookupString(three key columns) looks up a row source with three key-columns for the value resultColumn
lookup(String rowsourceName, String keyColumn1, String keyColumn2, String keyColumn3, String resultColumn)