diff --git a/NAMESPACE b/NAMESPACE
index 48a9429f..e627383e 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -19,7 +19,6 @@ export(problems)
 export(read_ct_spec)
 export(read_ct_spec_example)
 export(read_domain_example)
-export(rec_vars)
 export(sbj_vars)
 importFrom(rlang,"%||%")
 importFrom(rlang,":=")
diff --git a/R/derive_seq.R b/R/derive_seq.R
index 9e64de84..01e9e354 100644
--- a/R/derive_seq.R
+++ b/R/derive_seq.R
@@ -15,8 +15,7 @@
 #' @param tgt_var The target SDTM variable: a single string indicating the name
 #'   of the sequence number (`--SEQ`) variable, e.g. `"DSSEQ"`. Note that
 #'   supplying a name not ending in `"SEQ"` will raise a warning.
-#' @param rec_vars A character vector of record-level identifier variables. Use
-#' [rec_vars()] to quickly get the identifier variables for a given domain.
+#' @param rec_vars A character vector of record-level identifier variables.
 #' @param sbj_vars A character vector of subject-level identifier variables.
 #' @param start_at The sequence numbering starts at this value (default is `1`).
 #'
@@ -29,7 +28,8 @@
 #' (vs <- read_domain_example("vs"))
 #'
 #' # Derivation of VSSEQ
-#' derive_seq(tgt_dat = vs, tgt_var = "VSSEQ", rec_vars = rec_vars("VS"))
+#' rec_vars <- c("STUDYID", "USUBJID", "VSTESTCD", "VSDTC", "VSTPTNUM")
+#' derive_seq(tgt_dat = vs, tgt_var = "VSSEQ", rec_vars = rec_vars)
 #'
 #' # An APSC raw data set example
 #' (apsc <- read_domain_example("apsc"))
diff --git a/R/rec_vars.R b/R/rec_vars.R
deleted file mode 100644
index 18cb94c6..00000000
--- a/R/rec_vars.R
+++ /dev/null
@@ -1,37 +0,0 @@
-#' Record-level key variables
-#'
-#' [rec_vars()] returns the set of variable names that uniquely define
-#' a record in a given SDTM domain.
-#'
-#' @param domain An SDTM domain in abbreviated form, e.g. `"DM"` (Demographics)
-#'   or `"CM"` (Concomitant Medications).
-#'
-#' @returns A character vector of variable names.
-#'
-#' @examples
-#' rec_vars("DM")
-#'
-#' rec_vars("AE")
-#'
-#' @export
-rec_vars <- function(domain) {
-
-  domain <- toupper(domain)
-  domain <- rlang::arg_match(domain, values = names(domain_record_vars))
-  domain_record_vars[[domain]]
-}
-
-#' Subject-level key variables
-#'
-#' [sbj_vars()] returns the set of variable names that uniquely define
-#' a subject.
-#'
-#' @returns A character vector of variable names.
-#'
-#' @examples
-#' sbj_vars()
-#'
-#' @export
-sbj_vars <- function() {
-  c("STUDYID", "USUBJID")
-}
diff --git a/R/sbj_vars.R b/R/sbj_vars.R
new file mode 100644
index 00000000..96871eb1
--- /dev/null
+++ b/R/sbj_vars.R
@@ -0,0 +1,14 @@
+#' Subject-level key variables
+#'
+#' [sbj_vars()] returns the set of variable names that uniquely define
+#' a subject.
+#'
+#' @returns A character vector of variable names.
+#'
+#' @examples
+#' sbj_vars()
+#'
+#' @export
+sbj_vars <- function() {
+  c("STUDYID", "USUBJID")
+}
diff --git a/R/sysdata.rda b/R/sysdata.rda
deleted file mode 100644
index 9c1010d3..00000000
Binary files a/R/sysdata.rda and /dev/null differ
diff --git a/data-raw/domain_record_vars.R b/data-raw/domain_record_vars.R
deleted file mode 100644
index c97a8d3f..00000000
--- a/data-raw/domain_record_vars.R
+++ /dev/null
@@ -1,19 +0,0 @@
-# Record variables for SDTM domains
-# Original file provided by Edgar Manukyan (Roche).
-# Context: https://github.com/pharmaverse/sdtm.oak/issues/15
-# Source URL: https://github.com/pharmaverse/sdtm.oak/files/15326343/domain_key_variables.2.csv
-#
-# Author: Ramiro Magno (Pattern Institute)
-#
-library(tidyverse)
-path <- here::here("data-raw/domain_record_vars.csv.xz")
-
-tbl <-
-  readr::read_csv(path, col_names = TRUE, col_types = "cc") |>
-  dplyr::mutate(key_variables = strsplit(key_variables, "|", fixed = TRUE))
-
-domain_record_vars <- setNames(tbl$key_variables, tbl$domain)
-
-# `domain_record_vars` is an internal data set but can be accessed via
-# `rec_vars()`.
-usethis::use_data(domain_record_vars, internal = TRUE)
diff --git a/data-raw/domain_record_vars.csv.xz b/data-raw/domain_record_vars.csv.xz
deleted file mode 100644
index bac3eb0f..00000000
Binary files a/data-raw/domain_record_vars.csv.xz and /dev/null differ
diff --git a/man/derive_seq.Rd b/man/derive_seq.Rd
index 2e31c8ca..ae65ceae 100644
--- a/man/derive_seq.Rd
+++ b/man/derive_seq.Rd
@@ -19,8 +19,7 @@ derive_seq(
 of the sequence number (\code{--SEQ}) variable, e.g. \code{"DSSEQ"}. Note that
 supplying a name not ending in \code{"SEQ"} will raise a warning.}
 
-\item{rec_vars}{A character vector of record-level identifier variables. Use
-\code{\link[=rec_vars]{rec_vars()}} to quickly get the identifier variables for a given domain.}
+\item{rec_vars}{A character vector of record-level identifier variables.}
 
 \item{sbj_vars}{A character vector of subject-level identifier variables.}
 
@@ -47,7 +46,8 @@ according to grouping variables indicated in \code{rec_vars}.
 (vs <- read_domain_example("vs"))
 
 # Derivation of VSSEQ
-derive_seq(tgt_dat = vs, tgt_var = "VSSEQ", rec_vars = rec_vars("VS"))
+rec_vars <- c("STUDYID", "USUBJID", "VSTESTCD", "VSDTC", "VSTPTNUM")
+derive_seq(tgt_dat = vs, tgt_var = "VSSEQ", rec_vars = rec_vars)
 
 # An APSC raw data set example
 (apsc <- read_domain_example("apsc"))
diff --git a/man/rec_vars.Rd b/man/rec_vars.Rd
deleted file mode 100644
index 1557c012..00000000
--- a/man/rec_vars.Rd
+++ /dev/null
@@ -1,25 +0,0 @@
-% Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/rec_vars.R
-\name{rec_vars}
-\alias{rec_vars}
-\title{Record-level key variables}
-\usage{
-rec_vars(domain)
-}
-\arguments{
-\item{domain}{An SDTM domain in abbreviated form, e.g. \code{"DM"} (Demographics)
-or \code{"CM"} (Concomitant Medications).}
-}
-\value{
-A character vector of variable names.
-}
-\description{
-\code{\link[=rec_vars]{rec_vars()}} returns the set of variable names that uniquely define
-a record in a given SDTM domain.
-}
-\examples{
-rec_vars("DM")
-
-rec_vars("AE")
-
-}
diff --git a/man/sbj_vars.Rd b/man/sbj_vars.Rd
index 57b04ed6..80f8b5b2 100644
--- a/man/sbj_vars.Rd
+++ b/man/sbj_vars.Rd
@@ -1,5 +1,5 @@
 % Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/rec_vars.R
+% Please edit documentation in R/sbj_vars.R
 \name{sbj_vars}
 \alias{sbj_vars}
 \title{Subject-level key variables}