docs: fix terminology, core types, and codec examples

src/explanation/custom-codecs.md

@@ -42,7 +42,7 @@ class MyCodec(dj.Codec):
     """Store custom objects."""
     name = "mytype"  # Used as <mytype> in definitions
 
-    def get_dtype(self, is_external: bool) -> str:
+    def get_dtype(self, is_store: bool) -> str:
         """Return storage type."""
         return "<blob>"  # Chain to blob serialization
 
@@ -78,9 +78,9 @@ class GraphCodec(dj.Codec):
     """Store NetworkX graphs as adjacency data."""
     name = "graph"
 
-    def get_dtype(self, is_external: bool) -> str:
-        # Store as blob (internal) or hash-addressed (external)
-        return "<hash>" if is_external else "<blob>"
+    def get_dtype(self, is_store: bool) -> str:
+        # Store as blob (internal) or blob@ (external)
+        return "<blob@>" if is_store else "<blob>"
 
     def encode(self, graph, *, key=None, store_name=None):
         """Serialize graph to dict."""
@@ -136,10 +136,10 @@ class BamCodec(dj.Codec):
     """Store BAM alignments."""
     name = "bam"
 
-    def get_dtype(self, is_external: bool) -> str:
-        if not is_external:
+    def get_dtype(self, is_store: bool) -> str:
+        if not is_store:
             raise dj.DataJointError("<bam> requires external storage: use <bam@>")
-        return "<object>"  # Path-addressed storage for file structure
+        return "<object@>"  # Path-addressed storage for file structure
 
     def encode(self, alignments, *, key=None, store_name=None):
         """Write alignments to BAM format."""
@@ -162,8 +162,8 @@ class MedicalImageCodec(dj.Codec):
     """Store medical images with metadata."""
     name = "medimg"
 
-    def get_dtype(self, is_external: bool) -> str:
-        return "<hash>" if is_external else "<blob>"
+    def get_dtype(self, is_store: bool) -> str:
+        return "<blob@>" if is_store else "<blob>"
 
     def encode(self, image, *, key=None, store_name=None):
         """Serialize SimpleITK image."""
@@ -197,7 +197,7 @@ graph LR
 class CompressedGraphCodec(dj.Codec):
     name = "cgraph"
 
-    def get_dtype(self, is_external: bool) -> str:
+    def get_dtype(self, is_store: bool) -> str:
         return "<graph>"  # Chain to graph codec
 
     def encode(self, graph, *, key=None, store_name=None):
@@ -216,8 +216,8 @@ class CompressedGraphCodec(dj.Codec):
 class SmallDataCodec(dj.Codec):
     name = "small"
 
-    def get_dtype(self, is_external: bool) -> str:
-        if is_external:
+    def get_dtype(self, is_store: bool) -> str:
+        if is_store:
             raise dj.DataJointError("<small> is internal-only")
         return "json"
 ```
@@ -228,10 +228,10 @@ class SmallDataCodec(dj.Codec):
 class LargeDataCodec(dj.Codec):
     name = "large"
 
-    def get_dtype(self, is_external: bool) -> str:
-        if not is_external:
+    def get_dtype(self, is_store: bool) -> str:
+        if not is_store:
             raise dj.DataJointError("<large> requires @: use <large@>")
-        return "<object>"
+        return "<object@>"
 ```
 
 ### Both Modes
@@ -240,8 +240,8 @@ class LargeDataCodec(dj.Codec):
 class FlexibleCodec(dj.Codec):
     name = "flex"
 
-    def get_dtype(self, is_external: bool) -> str:
-        return "<hash>" if is_external else "<blob>"
+    def get_dtype(self, is_store: bool) -> str:
+        return "<blob@>" if is_store else "<blob>"
 ```
 
 ## Validation

src/how-to/create-custom-codec.md

@@ -58,16 +58,16 @@ Return the storage type:
 ```python
 def get_dtype(self, is_store: bool) -> str:
     if is_store:
-        return "<hash>"  # Hash-addressed storage
-    return "bytes"       # Inline database blob
+        return "<blob@>"  # Blob in object storage
+    return "bytes"        # Inline database blob
 ```
 
 Common return values:
 
 - `"bytes"` — Binary in database
 - `"json"` — JSON in database
-- `"<blob>"` — Chain to blob codec (hash-addressed when `@`)
-- `"<hash>"` — Hash-addressed storage
+- `"<blob>"` — Chain to blob codec (internal storage)
+- `"<blob@>"` — Blob in object storage
 
 ### `encode(value, *, key=None, store_name=None)`
 
@@ -135,7 +135,7 @@ class ZarrCodec(dj.Codec):
     def get_dtype(self, is_store: bool) -> str:
         if not is_store:
             raise DataJointError("<zarr> requires @ (store only)")
-        return "<object>"  # Schema-addressed storage
+        return "<object@>"  # Schema-addressed storage
 
     def encode(self, path, *, key=None, store_name=None):
         return path  # Path to zarr directory

src/tutorials/advanced/custom-codecs.ipynb

@@ -113,7 +113,7 @@
     "@schema\n",
     "class Connectivity(dj.Manual):\n",
     "    definition = \"\"\"\n",
-    "    conn_id : int\n",
+    "    conn_id : uint16\n",
     "    ---\n",
     "    network : <graph>\n",
     "    \"\"\""
@@ -253,7 +253,7 @@
     "@schema\n",
     "class Unit(dj.Manual):\n",
     "    definition = \"\"\"\n",
-    "    unit_id : int\n",
+    "    unit_id : uint16\n",
     "    ---\n",
     "    spikes : <spike_train>\n",
     "    \"\"\"\n",
@@ -304,4 +304,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 5
-}
+}

src/tutorials/advanced/sql-comparison.ipynb

@@ -1235,7 +1235,7 @@
     "# Restriction: filters Session to rows matching the Subject query  \n",
     "Session & (Subject & {'species': 'mouse'})\n",
     "\n",
-    "# Antijoin: Session rows NOT matching any Subject (none here, all subjects exist)\n",
+    "# Anti-restriction: Session rows NOT matching any Subject (none here, all subjects exist)\n",
     "Session - Subject"
    ]
   },
@@ -2583,7 +2583,7 @@
     "| `WHERE condition` | `& {'col': value}` or `& 'expr'` | Restriction |\n",
     "| `JOIN ... USING` | `Table1 * Table2` | Natural join |\n",
     "| `GROUP BY ... AGG()` | `.aggr(Table, alias='agg()')` | Aggregation |\n",
-    "| `NOT IN (subquery)` | `Table1 - Table2` | Antijoin |\n",
+    "| `NOT IN (subquery)` | `Table1 - Table2` | Anti-restriction |\n",
     "| `UNION` | `Table1 + Table2` | Union |"
    ]
   },