Lossless CDISC-Native Input and Output for Clinical Datasets // Reads and writes clinical-trial datasets losslessly across 'SAS' XPORT (XPT), Clinical Data Interchange Standards Consortium (CDISC) Dataset-JSON, and 'Apache Parquet', applying a specification to produce submission-ready Study Data Tabulation Model (SDTM) and Analysis Data Model (ADaM) datasets. A single canonical metadata model carries labels, CDISC data types, lengths, 'SAS' display formats, controlled- terminology references, and sort keys identically across every format, so conversion between any two formats is lossless by construction. Pure 'R' and lightweight, with no external 'SAS' or 'Java' runtime. Implements the published format specifications for CDISC Dataset-JSON (https://cdisc- org.github.io/DataExchange-DatasetJson/doc/dataset- json1-1.html) and 'SAS' XPORT (https://www.loc.gov/preservation /digital/formats/fdd/fdd000466.shtml).