7.2. Criteria Determination
The criteria field varies according to whether it is the first field in the shipping file exactly matching the mode identifier. In that case, it is called the main criterion. If it is in subsidiary shipping lines matching the mode (with optional appended digits), it is called a qualifying criterion. The difference is that the main criterion returns the basis for the calculation (i.e., weight or quantity), while the qualifying criterion determines whether the individual line may match the conditions.
The return must be one of:
The literal value quantity as the main criterion will simply count the number of items in the shopping cart and return it as the accumulated criteria. If using a database table field named quantity, use the table::field notation.
o <field name> or <table>::<field name>
A valid database field (column) name as main criterion will cause the number of items in the shopping cart to be multiplied by the value of the field for each item to obtain the accumulated criteria. If the table is not supplied, defaults to the first ProductFiles table.
Where n.nn is any number, it will be directly used as the accumulated criteria. This can be effectively returned from a Perl subroutine or Interchange [calc][item-list] ... [/item-list][/calc] to create custom shipping routines.
IMPORTANT NOTE: The above only applies to the first field that matches the shipping mode exactly. Following criteria fields contain qualifier matching strings.