sdtm_se.RdSubject Elements data frame - One record per actual Element per subject
sdtm_sea data frame with 752 rows and 9 columns. See https://github.com/SafetyGraphics/safetyData/blob/main/data-raw/sdtm/README.md for more details and full data specification. Columns:
 STUDYID text - Study Identifier
 DOMAIN text - Domain Abbreviation
 USUBJID text - Unique Subject Identifier
 SESEQ integer - Sequence Number
 ETCD text - Element Code
 ELEMENT text - Description of Element
 SESTDTC date - Start Date/Time of Element
 SEENDTC date - End Date/Time of Element
 SEUPDES text - Description of Unplanned Element