This field is provided for those instances where the reference to a record is made up of several parts that are input separately. For instance, the reference to a particular issue of a magazine may be made up of the magazine code, followed by the date it is issued. Together, these make up the key to the record that will hold the details on that particular issue. This type of key is known as a composite key.

PARADYME allows the user to specify that several 'S' type inputs be treated as component parts of a composite key. The parts are joined together to form the key to the relevant record. The problem arises when this key needs to be broken down into its component parts, for instance, when each component part is required as a dictionary item for reporting purposes. It may be that each part of the key is a fixed length, so each part occupies a definite position. However, with PICK being able to cater for variable length fields, this may not always be the case. Indeed, it is a desirable design feature not to assume that a given field will always be a fixed length. In such a situation the user may specify a KEY CONCAT CHARACTER that is inserted in between each of the component fields as a way of separating the fields.

If for instance, we take the example of an issue ID. The user enter a magazine code of WOM and an issue date of 19 MAY 85. The KEY CONCAT CHARACTER is * , the key to the record become WOM*19 MAY 85 . If the character is '-' the key becomes WOM-19 MAY 85 . The default for this field is null, i.e. no character is inserted, that is it assumes that the fields are fixed length. In the example above, this gives a key of WOM19 MAY 85.

Note that the example uses a date in external format. This is NOT recommended practice in systems design. One should always use the internal format when storing dates. The external format is only used in this example for clarity.

If a KEY CONCAT CHARACTER is specified, it becomes a simple matter of using the FIELD function to extract each component field from the key in a Data/Basic routine or the G(roup) extraction function in ACCESS.