diff --git a/app.py b/app.py
index e4dae99..f5b3c6e 100644
--- a/app.py
+++ b/app.py
@@ -5,7 +5,9 @@ import logging
 import logging.config
 import os
 
-from flask import (Flask, request, jsonify, abort, render_template)
+from collections import defaultdict
+
+from flask import (Flask, request, jsonify, abort, render_template, url_for)
 
 from ltsdb_json import LTS
 from dashboard import Dashboard
@@ -152,3 +154,71 @@ def dashboard_index():
 def dashboard_file(dashboard):
     d = Dashboard("dashboards/" + dashboard + ".json")
     return d.as_html()
+
+@app.get("/nav")
+def nav():
+    # Start with a list of all dimensions, the number of matching time series
+    # and a truncated list of series.
+    # If a dimension is chosen, display a choice of members
+    # choosing one or more members goes back to the list of
+    # (remaining) dimensions
+    with open("data/.index") as fh:
+        fcntl.flock(fh, fcntl.LOCK_SH)
+        index = json.load(fh)
+    timeseries = None
+    for k, v in request.args.lists():
+        if k[0] == ".":
+            continue
+        log.debug("search: %s -> %s", k, v)
+        if timeseries is None:
+            timeseries = set()
+            log.debug("search: %s: %s", k, index[k])
+            for m in v:
+                timeseries |= set(index[k][m])
+        else:
+            filter = set()
+            for m in v:
+                filter |= set(index[k][m])
+            timeseries &= filter
+    if timeseries is None:
+        timeseries = set()
+        for mc in index.values():
+            for tsl in mc.values():
+                timeseries |= set(tsl)
+    if d := request.args.get(".m"):
+        members = []
+        for m, tsl in index[d].items():
+            if set(tsl) & timeseries:
+                members.append(m)
+        return render_template("nav_member_select.html", dimension=d, members=members)
+    else:
+        params = request.args.to_dict(flat=False)
+        matching_dimensions = defaultdict(int)
+        for d, mc in index.items():
+            if d in params:
+                continue
+            for m, tsl in mc.items():
+                mtsl = set(tsl) & timeseries
+                if mtsl:
+                    matching_dimensions[d] += len(mtsl)
+        matching_dimensions_list = []
+        for d in matching_dimensions:
+            params[".m"] = d
+            url = url_for("nav", **params)
+            app.logger.debug(f"{d=} {url=}")
+            matching_dimensions_list.append(
+                {"name": d, "count": matching_dimensions[d], "url": url}
+            )
+        total_timeseries = len(timeseries)
+        timeseries = [LTS(id=ts) for ts in list(timeseries)[:100]]
+        return render_template(
+                    "nav_dimension_list.html",
+                    matching_dimensions=matching_dimensions_list,
+                    timeseries=timeseries, total_timeseries=total_timeseries)
+
+
+
+
+
+
+    #