Card and column definitions are necessary if you want to use the Quantum DSC to write response data to a Quantum-format ASCII file and a matching Quantum specification. The card and column definitions define how the case data is to be organized in the ASCII file. The card and column definitions are stored as MDM custom properties in the MDM Document. The custom properties are read, for example, by Quantum DSC when it writes case data to a Quantum-format ASCII file and by UNICOM Intelligence Interviewer - Paper when it displays the card and column information in a paper questionnaire for use by data entry staff. Card and column definitions are also used by the Triple-S DSC to define the format of the Triple-S case data being read or written.

UNICOM Intelligence components such as the Quantum DSC read the card and column custom properties from the DataSourceProperties collections on the Document, VariableInstance, and ElementInstance objects. Because DataSourceProperties are unversioned, using them rather than the Properties collections makes it easier to handle card and column definitions when variables and categories are added and deleted in different versions of the MDM Document. However, DataSourceProperties are specific to a particular DataSource object within the MDM Document, and they are only visible when the same DataSource object is set as the current DataSource in the MDM Document.

Note that the Metadata Model to Quantum component writes the custom properties to the DataSourceProperties collection on the Element rather than the ElementInstance object. However, the MDM inheritance rules mean that DataSourceProperties on the ElementInstance object inherits from the Element object and so this change is largely invisible, but has the advantage that the categories in category lists that are shared between questions have the same punch codes in each question and has led to a significant reduction in .mdd file size in projects that have large numbers or grids, loops, or defined lists.

You can set up card and column definitions in a number of ways: