About DID elements

This section describes the various elements that constitute a DID.

A DID structure is composed of entries (files and folders), subentries, and functions.

An entry defines what data is retrieved and enables you to retrieve the data from a data source. An entry definition consists of Fields, a data retrieval method, and a set of formal parameters. Formal parameters are required when the DID entry is used in a Master Template with the PATH/PAR construction. Also, you can define an entry as a main entry to use as a starting point for the data retrieval in a Master Template.

The data that an entry retrieves can conform to a database record, such as a table in an SQL database. It may not coincide with an actual table in the database, but can present a pre-processed, simplified or summarized view of a single table or a collection of tables. For information on the syntax of an entry, see Entries.

An entry can have a number of subentries. Also, you can export entries defined in a DID module and import them as subentries in another DID module (see Subentries). A subentry definition consists of actual parameters. The actual parameters are the values of the formal parameters used to access a particular subentry of an entry.

A data set retrieved by an entry is contained in a Field, and the retrieved data can only be accessed through these Fields. Each Field has a data type: In the KCM Template scripting language, numerical Fields are mapped to the NUMBER type, while alphanumerical Fields are mapped to the TEXT type. For information on the syntax of a Field, see Fields.

To perform actions on a host system with a DID, use DID defined functions. For example, you can calculate totals, subtotals or averages, or update records in a database. For information on the syntax of the DID functions, see DID defined functions.

Additionally, an entry describes the input and output parameters for the data retrieval method, which is the core of the data-text merge process. Depending on the connection type, one or more mechanisms are available for data retrieval. The result of data retrieval is a data set that conforms to the Field definitions of the entry.

A data retrieval method has a variant called key retrieval. It determines the Fields to show in the Key Selection window when the Master Template is run and the actual parameters to pass to the data retrieval method.