6.4.17 The Operator +

This operator may only be used in the following ways:

string1 + string2

This yields the concatenation of string1 and string2.

list1 + list2

This yields the concatenation of list1 and list2.

number1 + number2

This yields the sum of number1 and number2.

record1 + record2

This yields a record wich consists of all attributes of record1 and record2. If record1 and record2 have a common attribute names, the corresponding attributes in the result record will have the attribute values from record2, in contrast to the operator *.