Which CDISC filename contains key variable attributes and controlled terminology?

The correct choice, DEFINE.XML, is a key file in the Clinical Data Interchange Standards Consortium (CDISC) framework. This file is crucial because it provides essential information about the study's datasets, including variable attributes such as metadata, the meanings of variables, their content, and the associated controlled terminology.

DEFINE.XML serves as a comprehensive guide that illustrates how variables should be interpreted and utilized within the context of clinical trials. It outlines the format of the datasets and offers clarity regarding the relationships between different data elements. By standardizing how these attributes are documented, DEFINE.XML improves data consistency and enhances communication between data users and analysts.

Other options either serve different purposes or do not extend to include both variable attributes and controlled terminology comprehensively. For instance, ADAM.XML focuses specifically on the Analysis Data Model, providing specifics about analysis datasets rather than broader variable attributes. SASDATA.XML is not a standard CDISC file used widely in regulatory submissions, and SDTM.PDF is a document format that usually contains guidelines for the SDTM standard but does not function as a comprehensive file for key variable attributes and terminology as DEFINE.XML does.