diff --git a/web/scripts/hangar.test.mjs b/web/scripts/hangar.test.mjs
index 02684e5..7b1e85c 100644
--- a/web/scripts/hangar.test.mjs
+++ b/web/scripts/hangar.test.mjs
@@ -417,6 +417,29 @@ test("a chassis with a space is searchable by name", () => {
   );
 });
 
+test("the filter reference says what is not supported yet, and marks it", async () => {
+  // A player who tries equipment:"ER PPC" and gets nothing deserves to know
+  // whether they got the syntax wrong or asked the library for something it
+  // does not carry.
+  const hangar = await readFile(`${web}src/screens/hangar.ts`, "utf8");
+  for (const missing of ["equipment", "quirks", "alpha", "engine", "faction"]) {
+    assert.match(
+      hangar,
+      new RegExp(`soon\\("${missing}"`),
+      `${missing} is not listed as unsupported`,
+    );
+  }
+  assert.match(hangar, /coming soon/, "nothing marks the unsupported terms");
+  // And they are not silently accepted by the parser either.
+  assert.equal(parseQuery('equipment:"ER PPC"').filters.length, 0);
+});
+
+test("the reference is a dialog rather than a caption", async () => {
+  const hangar = await readFile(`${web}src/screens/hangar.ts`, "utf8");
+  assert.match(hangar, /el\("dialog", \{ className: "hangar-help" \}/);
+  assert.match(hangar, /syntaxDialog\.showModal\(\)/);
+});
+
 test("every filter the builder can make is a term the box can hold", async () => {
   // The builder writes into the query rather than holding a filter of its
   // own, which is what keeps "expressible as text" true by construction
diff --git a/web/src/screens/hangar.ts b/web/src/screens/hangar.ts
index 9a4b206..e62a94f 100644
--- a/web/src/screens/hangar.ts
+++ b/web/src/screens/hangar.ts
@@ -63,6 +63,23 @@ const PAGE = 12;
 /** How much accent each segment keeps, stepping down along the strip. */
 const RAMP = [100, 86, 72, 58, 46, 36, 28];
 
+/** One worked example: the query, and what it asks for. */
+function example(query: string, means: string): HTMLElement {
+  return el("li", {}, [
+    el("code", { textContent: query }),
+    el("span", { className: "hint", textContent: ` — ${means}` }),
+  ]);
+}
+
+/** One question the library cannot answer yet, and what it would look like. */
+function soon(key: string, query: string, means: string): HTMLElement {
+  return el("li", {}, [
+    el("code", { className: "hangar-soon-term", textContent: query }),
+    el("span", { className: "hint", textContent: ` — ${means}` }),
+    el("span", { className: "hangar-soon-mark", textContent: "coming soon" }),
+  ]);
+}
+
 /** A design's picture, or a plate where the release has none. */
 function sprite(unit: Unit, size: number): HTMLElement {
   if (!unit.sprite) {
@@ -138,24 +155,66 @@ export function hangarScreen(): Node[] {
   /** The filters in the box, as something to read and remove. */
   const pills = el("div", { className: "hangar-pills" });
 
-  /** What the box takes, said once rather than guessed at. */
-  const syntax = el("p", { className: "hint hangar-syntax" }, [
-    document.createTextNode("Filters: "),
-    el("code", { textContent: "era<=3025" }),
-    document.createTextNode(" "),
-    el("code", { textContent: "bv<=1500" }),
-    document.createTextNode(" "),
-    el("code", { textContent: "class:heavy" }),
-    document.createTextNode(" "),
-    el("code", { textContent: "tech:clan" }),
-    document.createTextNode(" "),
-    el("code", { textContent: "jump>0" }),
-    document.createTextNode(
-      `. Any of ${FILTER_KEYS.join(", ")}, with : = < <= > >=.`,
-    ),
-  ]);
+  const closeHelp = el("button", {
+    type: "button",
+    className: "secondary small-btn",
+    textContent: "Close",
+  });
+
+  const help = el("button", {
+    type: "button",
+    className: "secondary small-btn hangar-help-open",
+    textContent: "Filters",
+  });
 
-  /** What the target is imposing on the search, when it is locked. */
+  /**
+   * What the box takes, and what it does not take yet.
+   *
+   * A dialog rather than a line of small print under the search: the list is
+   * twenty keys long and the screen is a workbench, so it belongs where it
+   * can be read and then put away. The unsupported half is in it on purpose —
+   * a player who tries `equipment:"ER PPC"` and gets nothing deserves to know
+   * whether they got the syntax wrong or asked for something the library does
+   * not carry.
+   */
+  const syntaxDialog = el("dialog", { className: "hangar-help" }, [
+    el("div", { className: "hangar-help-body" }, [
+      el("h2", { textContent: "Searching the library" }),
+      el("p", {
+        textContent:
+          "Bare words match a design's name. A term filters a column: key, then one of : = < <= > >=, then a value. Everything combines with and.",
+      }),
+      el("ul", { className: "hangar-help-examples" }, [
+        example("atlas", "every Atlas"),
+        example("bv<=1500", "nothing dearer than 1,500 battle value"),
+        example(
+          "era<=3025 tech:inner",
+          "Inner Sphere designs of 3025 or earlier",
+        ),
+        example("class:heavy jump>0", "heavies that jump"),
+        example('chassis:"black hawk"', "a name with a space in it, quoted"),
+        example("role:brawler mass>=70", "brawlers of 70 tons and up"),
+      ]),
+      el("h3", { textContent: "Every key" }),
+      el("p", { className: "hangar-help-keys" }, [
+        el("code", { textContent: FILTER_KEYS.join(", ") }),
+      ]),
+      el("h3", { textContent: "Not yet" }),
+      el("p", {
+        textContent:
+          "These are questions the library cannot answer yet. Each one needs a column helm does not publish in the index — the data exists in its database, so the work is deciding what a browser should carry rather than finding it.",
+      }),
+      el("ul", { className: "hangar-help-soon" }, [
+        soon("equipment", 'equipment:"ER PPC"', "what a design carries"),
+        soon("quirks", "quirks:battlefists", "MegaMek's per-design quirks"),
+        soon("damage", "damage9>=20", "damage at a range band"),
+        soon("alpha", "alpha:3/3/2", "the Alpha Strike conversion"),
+        soon("engine", "engine:xl", "engine, structure and armour types"),
+        soon("faction", "faction:steiner", "who fielded it, and when"),
+      ]),
+      el("div", { className: "row hangar-help-actions" }, [closeHelp]),
+    ]),
+  ]); /** What the target is imposing on the search, when it is locked. */
   const imposed = el("div", { className: "hangar-imposed" });
 
   /** Put a query back in the box and redraw from it. */
@@ -596,12 +655,12 @@ export function hangarScreen(): Node[] {
     el("div", { className: "hangar-meter" }, [totals, strip, warning]),
     el("div", { className: "hangar-panes" }, [
       el("section", { className: "card hangar-library" }, [
-        el("div", { className: "hangar-search-row" }, [searchBox, found]),
+        el("div", { className: "hangar-search-row" }, [searchBox, help, found]),
         pills,
         builder,
         imposed,
-        syntax,
         results,
+        syntaxDialog,
         el("div", { className: "hangar-ways-in" }, [
           el(
             "a",
@@ -634,6 +693,13 @@ export function hangarScreen(): Node[] {
     ]),
   ]);
 
+  help.addEventListener("click", () => {
+    syntaxDialog.showModal();
+  });
+  closeHelp.addEventListener("click", () => {
+    syntaxDialog.close();
+  });
+
   draw();
 
   void currentSession()
diff --git a/web/src/styles.css b/web/src/styles.css
index e299e5f..f7aa2fd 100644
--- a/web/src/styles.css
+++ b/web/src/styles.css
@@ -6152,15 +6152,11 @@ footer .debug {
   margin-top: 0.35rem;
 }
 
-/* What the box takes, and what the target is imposing on it. Both are small
-   print under the search: a player who knows the syntax should not have to
-   read them, and one who does not should not have to guess. */
-.hangar-syntax {
-  margin: 0.1rem 0 0.35rem;
-  font-size: 0.78rem;
-}
-
-.hangar-syntax code,
+/* What the target is imposing on the search. Small print under the box: a
+   player who knows the syntax should not have to read it, and one who does
+   not should not have to guess why a search answered the way it did. The
+   syntax itself is a dialog behind the Filters button — twenty keys is a
+   reference, not a caption. */
 .hangar-term {
   font-family: var(--font-data);
   font-size: 0.9em;
@@ -6255,3 +6251,90 @@ footer .debug {
 .hangar-value {
   width: 9rem;
 }
+
+/* The filter reference. A dialog because it is a page of it, and because a
+   workbench should be able to put its manual away. */
+.hangar-help::backdrop {
+  background: rgb(0 0 0 / 55%);
+}
+
+.hangar-help {
+  max-width: min(42rem, calc(100vw - 2rem));
+  color: var(--ink);
+  background: var(--panel);
+  border: 1px solid var(--line);
+  border-radius: var(--radius);
+}
+
+.hangar-help-body {
+  display: flex;
+  flex-direction: column;
+  gap: 0.6rem;
+  padding: 1.25rem;
+}
+
+.hangar-help-body h2 {
+  margin: 0;
+  font-size: 1.1rem;
+}
+
+.hangar-help-body h3 {
+  margin: 0.4rem 0 0;
+  font-size: 0.85rem;
+}
+
+.hangar-help-body p {
+  margin: 0;
+  font-size: 0.9rem;
+}
+
+.hangar-help-examples,
+.hangar-help-soon {
+  display: flex;
+  flex-direction: column;
+  gap: 0.3rem;
+  margin: 0;
+  padding: 0;
+  list-style: none;
+  font-size: 0.9rem;
+}
+
+.hangar-help-examples code,
+.hangar-help-soon code,
+.hangar-help-keys code {
+  font-family: var(--font-data);
+  font-size: 0.85em;
+  padding: 0.05rem 0.3rem;
+  background: var(--bg);
+  border: 1px solid var(--line);
+  border-radius: 3px;
+}
+
+.hangar-help-keys code {
+  display: block;
+  padding: 0.4rem 0.5rem;
+  line-height: 1.5;
+}
+
+/* Dimmed, and marked: a term that cannot work yet should not read like one
+   that can. */
+.hangar-help-soon li {
+  opacity: 0.75;
+}
+
+.hangar-soon-mark {
+  margin-left: 0.4rem;
+  font-family: var(--font-labels);
+  font-size: 0.58rem;
+  letter-spacing: 0.1em;
+  text-transform: uppercase;
+  color: var(--stamp);
+  border: 1px solid var(--stamp);
+  border-radius: 3px;
+  padding: 0.05rem 0.3rem;
+}
+
+.hangar-help-actions {
+  justify-content: flex-end;
+  margin-top: 0.4rem;
+}