diff --git a/test-linuxcnc-rs274-native.sh b/test-linuxcnc-rs274-native.sh
index 47054e6..9201db4 100755
--- a/test-linuxcnc-rs274-native.sh
+++ b/test-linuxcnc-rs274-native.sh
@@ -1062,6 +1062,22 @@ cp "$base_var_file" "$var_file"
 CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_g52_offset.ngc >"$output_dir/cnc_sim_linuxcnc_g52_offset.json"
 CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_g52_xz_nurbs.ngc >"$output_dir/cnc_sim_linuxcnc_g52_xz_nurbs.json"
 CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_g62_xz_nurbs.ngc >"$output_dir/cnc_sim_linuxcnc_g62_xz_nurbs.json"
+# Source basis: LinuxCNC src/emc/rs274ngc/interp_read.cc read_n_number()
+# accepts and ignores the fractional suffix after an N word, preserves leading
+# zero line numbers, and has the >99999 range check disabled; execute_block()
+# in src/emc/rs274ngc/interp_execute.cc still tags canon output with the
+# interpreter sequence number.
+CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_fractional_linenumbers.ngc >"$output_dir/cnc_sim_linuxcnc_fractional_linenumbers.json"
+CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_extended_linenumbers.ngc >"$output_dir/cnc_sim_linuxcnc_extended_linenumbers.json"
+# Source basis: LinuxCNC src/emc/rs274ngc/interp_read.cc read_text()
+# calls close_and_downcase() to downcase words and remove spaces/tabs outside
+# comments before read_items() dispatches the words.
+CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_close_and_downcase_words.ngc >"$output_dir/cnc_sim_linuxcnc_close_and_downcase_words.json"
+# Source basis: LinuxCNC src/emc/rs274ngc/rs274ngc_pre.cc open() enables
+# percent-file mode when the first nonblank line is '%'; read_text() in
+# src/emc/rs274ngc/interp_read.cc returns INTERP_ENDFILE at the matching '%',
+# so later lines are ignored.
+CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_percent_file_ignores_trailing.ngc >"$output_dir/cnc_sim_linuxcnc_percent_file_ignores_trailing.json"
 CNC_SIM_RS274_NATIVE_OUTPUT_DIR="$output_dir" python3 - <<'PY'
 import json
 import os
@@ -1087,6 +1103,52 @@ required_motion = {"set-units", "set-plane", "set-spindle", "rapid", "set-feed",
 check(OUTPUT_DIR / "cnc_sim_linuxcnc_basic_motion.json", required_motion)
 check(OUTPUT_DIR / "cnc_sim_linuxcnc_basic_mill.json", required_motion | {"tool-change"})
 
+fractional_linenumbers = load("cnc_sim_linuxcnc_fractional_linenumbers.json")
+fractional_spindle_states = [
+    (event["line"], event["spindle"])
+    for event in fractional_linenumbers
+    if event["type"] == "set-spindle"
+]
+if fractional_spindle_states[:3] != [(1, 300), (2, 600), (3, 1200)]:
+    raise SystemExit(
+        "unexpected native fractional N-word spindle sequence: "
+        f"{fractional_spindle_states!r}"
+    )
+
+extended_linenumbers = load("cnc_sim_linuxcnc_extended_linenumbers.json")
+extended_spindle_states = [
+    (event["line"], event["spindle"])
+    for event in extended_linenumbers
+    if event["type"] == "set-spindle"
+]
+if extended_spindle_states[:3] != [(1, 111), (2, 222), (3, 333)]:
+    raise SystemExit(
+        "unexpected native extended N-word spindle sequence: "
+        f"{extended_spindle_states!r}"
+    )
+
+close_and_downcase_words = load("cnc_sim_linuxcnc_close_and_downcase_words.json")
+if not any(
+    event["type"] == "linear-feed" and
+    event["line"] == 3 and
+    event["end"]["x"] == 3 and
+    event["end"]["y"] == 4
+    for event in close_and_downcase_words
+):
+    raise SystemExit("missing native close_and_downcase mixed-case spaced-word move")
+
+percent_file = load("cnc_sim_linuxcnc_percent_file_ignores_trailing.json")
+percent_file_feeds = [
+    (event["line"], event["end"]["x"])
+    for event in percent_file
+    if event["type"] == "linear-feed"
+]
+if percent_file_feeds != [(4, 1)]:
+    raise SystemExit(
+        "unexpected native percent-file feed sequence: "
+        f"{percent_file_feeds!r}"
+    )
+
 block_delete_off = load("cnc_sim_linuxcnc_block_delete_off.json")
 if not any(
     event["type"] == "linear-feed" and event["line"] == 2 and event["end"]["x"] == 5
@@ -2896,3 +2958,7 @@ echo "dumped $output_dir/cnc_sim_linuxcnc_g92_restore.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_g52_offset.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_g52_xz_nurbs.json"
 echo "dumped $output_dir/cnc_sim_linuxcnc_g62_xz_nurbs.json"
+echo "dumped $output_dir/cnc_sim_linuxcnc_fractional_linenumbers.json"
+echo "dumped $output_dir/cnc_sim_linuxcnc_extended_linenumbers.json"
+echo "dumped $output_dir/cnc_sim_linuxcnc_close_and_downcase_words.json"
+echo "dumped $output_dir/cnc_sim_linuxcnc_percent_file_ignores_trailing.json"