diff --git a/experiments/exp5056_raw_web_markup_ppl.py b/experiments/exp5056_raw_web_markup_ppl.py
new file mode 100644
index 0000000000..006599ce86
--- /dev/null
+++ b/experiments/exp5056_raw_web_markup_ppl.py
@@ -0,0 +1,27 @@
+# Copyright The Marin Authors
+# SPDX-License-Identifier: Apache-2.0
+
+"""
+Registry helpers for raw web, markup, and image-text perplexity-gap slices.
+"""
+
+import os
+from collections.abc import Mapping
+
+from marin.evaluation.perplexity_gap import RawTextEvaluationDataset
+
+RAW_WEB_MARKUP_PREFIX = "raw_web_markup"
+
+ACTIVE_RAW_WEB_MARKUP_DATASETS: dict[str, RawTextEvaluationDataset] = {}
+
+
+def prefixed_raw_web_markup_validation_sets(
+    datasets: Mapping[str, RawTextEvaluationDataset],
+) -> dict[str, RawTextEvaluationDataset]:
+    """Prefix raw-web-markup slice names with ``raw_web_markup/``."""
+    return {os.path.join(RAW_WEB_MARKUP_PREFIX, slice_name): dataset for slice_name, dataset in datasets.items()}
+
+
+def raw_web_markup_raw_validation_sets() -> dict[str, RawTextEvaluationDataset]:
+    """Raw web/markup evaluation slices keyed by ``raw_web_markup/<slice>``."""
+    return prefixed_raw_web_markup_validation_sets(ACTIVE_RAW_WEB_MARKUP_DATASETS)
diff --git a/tests/evals/test_exp5056_raw_web_markup_ppl.py b/tests/evals/test_exp5056_raw_web_markup_ppl.py
new file mode 100644
index 0000000000..be842b01f8
--- /dev/null
+++ b/tests/evals/test_exp5056_raw_web_markup_ppl.py
@@ -0,0 +1,34 @@
+# Copyright The Marin Authors
+# SPDX-License-Identifier: Apache-2.0
+
+import os
+
+from experiments import exp5056_raw_web_markup_ppl as raw_web_markup
+from marin.evaluation.perplexity_gap import RawTextEvaluationDataset
+
+
+def test_prefixed_raw_web_markup_validation_sets_prefixes_each_slice() -> None:
+    warc = RawTextEvaluationDataset(input_path="raw/common_crawl/warc.jsonl.gz")
+    wat = RawTextEvaluationDataset(input_path="raw/common_crawl/wat.jsonl.gz")
+
+    prefixed = raw_web_markup.prefixed_raw_web_markup_validation_sets(
+        {
+            "cc_warc_html": warc,
+            "cc_wat_json": wat,
+        }
+    )
+
+    assert prefixed == {
+        os.path.join(raw_web_markup.RAW_WEB_MARKUP_PREFIX, "cc_warc_html"): warc,
+        os.path.join(raw_web_markup.RAW_WEB_MARKUP_PREFIX, "cc_wat_json"): wat,
+    }
+
+
+def test_raw_web_markup_raw_validation_sets_reads_active_registry(monkeypatch) -> None:
+    svg = RawTextEvaluationDataset(input_path="raw/svg_stack/svg.xml.jsonl.gz")
+
+    monkeypatch.setattr(raw_web_markup, "ACTIVE_RAW_WEB_MARKUP_DATASETS", {"svg_xml": svg})
+
+    assert raw_web_markup.raw_web_markup_raw_validation_sets() == {
+        os.path.join(raw_web_markup.RAW_WEB_MARKUP_PREFIX, "svg_xml"): svg
+    }