Show what type records are inside a schema

src/content/doc-surrealql/datamodel/ids.mdx

@@ -254,6 +254,34 @@ COMMIT TRANSACTION;
 RETURN person_id:counter.num;
 ```
 
+## Defining record IDs in a schema
+
+The type name of a record ID is `record`, which by default allows any sort of record.
+
+```surql
+DEFINE FIELD possessions ON TABLE person TYPE option<array<record>>;
+DEFINE FIELD friends ON TABLE person TYPE option<array<record<person>>>;
+
+CREATE person SET 
+    possessions = [ book:one, house:one],
+    friends = [ person:one, person:two ];
+```
+
+Be sure to use just `record` instead of `record<any>`, as `<any>` here would imply actual records of a table called `any`.
+
+```surql
+DEFINE FIELD possessions ON TABLE person TYPE option<array<record<any>>>;
+
+-- Won't work, 'book' and 'house' are not of table 'any'
+CREATE person SET 
+    possessions = [ book:one, house:one ];
+
+-- Actually expects this, which is probably
+-- not what the DEFINE FIELD intended
+CREATE person SET 
+    possessions = [ any:one, any:two ];
+```
+
 ## Learn more 
 
 Learn more about Record IDs [in this blogpost](/blog/the-life-changing-magic-of-surrealdb-record-ids#the-performance-at-scale) and on this [youtube video](https://www.youtube.com/watch?v=c0cqmWRYP8c).