diff --git a/3x5.js b/3x5.js
index e64d133..d4f8d04 100644
--- a/3x5.js
+++ b/3x5.js
@@ -1,4 +1,35 @@
-const h1 = document.createElement("h1");
-h1.textContent = "Hello, World!";
+/**
+ * @typedef {object} Card - Basic unit of information, also an "actor" in the programming system
+ * @property {number} id Unique identifier
+ * @property {Record<string, string>} fields Key-value properties on the card
+ * @property {string} code Eventually: a markdown string containing code, but for now, just code
+ */
 
-document.body.append(h1);
+/**
+ * Global state: a single card
+ * @type {Card}
+ */
+let theCard = {
+  id: 100,
+  fields: {},
+  code: `
+    h1 Hello, World!
+    para [2 + 2]
+    block {
+        This is a paragraph of text, with one [b bold] word. Yes, this means there has to be some magic in text processing...
+    }
+    block -red "Beware!"
+    block Wait, how do we distinguish a \{\} long string (text to put in a block) from a code block (with commands whose output goes in a block?)
+  `,
+};
+
+const state = document.createElement("pre");
+const display = document.createElement("blockquote");
+
+function render() {
+  state.textContent = JSON.stringify(theCard, null, 2);
+  display.innerHTML = "<em>Rendering not implemented</em>";
+}
+
+render();
+document.body.append(state, display);