diff --git a/tools/deploy/spritedata.ts b/tools/deploy/spritedata.ts
new file mode 100644
index 00000000..5be970fd
--- /dev/null
+++ b/tools/deploy/spritedata.ts
@@ -0,0 +1,65 @@
+
+type SpriteDataAttrs = {id : number | string,
+                        extra : [string, string][]};
+
+export class SpriteData {
+    public readonly id : number | string;
+    private extra : Map<string, string>;
+    
+    constructor({id, extra}: SpriteDataAttrs) {
+        this.id = id;
+        this.extra = new Map;
+        for (const [k,v] of extra) {
+            if (v === "") {
+                // Don't store empty entries. Can't just avoid set()-ing,
+                // because might set "" after another entry to blot it out
+                this.extra.delete(k);
+            } else {
+                this.extra.set(k, v);
+            }
+        }
+    }
+
+    get(x : string) : string {
+        return this.extra.get(x) ?? "";
+    }
+
+    [Symbol.iterator]() {
+        return this.extra[Symbol.iterator]();
+    }
+
+    static parse(s : string) {
+        const parts = s.split("-");
+        const id = parts[0].match(/^[0-9]+$/) ? parseInt(parts[0], 10) : parts[0];
+        const extra : [string, string][] = [];
+        for (const part of parts.slice(1)) {
+            if (part.length === 0)
+                throw new Error(`Can't parse ${s}`);
+            extra.push([part[0], part.slice(1)]);
+        }
+        return new SpriteData({id, extra});
+    }
+    
+    update({id, extra} : Partial<SpriteDataAttrs>) {
+        return new SpriteData({id : id ?? this.id,
+                               extra: [...this, ...(extra ?? [])]});
+    }
+    
+    format() {
+        let s = this.id.toString();
+        const extra = Array.from(this);
+        extra.sort(([k1,], [k2,]) => {
+            if (k1 < k2) {
+                return -1;
+            } else if (k1 > k2) {
+                return 1;
+            } else {
+                return 0;
+            }
+        });
+        for (const [k, v] of extra) {
+            s += `-${k}${v};`
+        }
+        return s;
+    }
+}