diff --git a/codecs/vlen-bytes/README.md b/codecs/vlen-bytes/README.md
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+# Vlen-bytes codec
+
+Defines an `array -> bytes` codec that serializes variable-length byte string arrays.
+
+## Codec name
+
+The value of the `name` member in the codec object MUST be `vlen-bytes`.
+
+## Configuration parameters
+
+None.
+
+## Example
+
+For example, the array metadata below specifies that the array contains variable-length byte strings:
+
+```json
+{
+    "data_type": "bytes",
+    "codecs": [{
+        "name": "vlen-bytes"
+    }],
+}
+```
+
+## Format and algorithm
+
+This is a `array -> bytes` codec.
+
+This codec is only compatible with the [`"bytes"`](../../data-types/bytes/README.md) data type.
+
+In the encoded format, each chunk is prefixed with a 32-bit little-endian unsigned integer (u32le) that specifies the number of elements in the chunk.
+This prefix is followed by a sequence of encoded elements in lexicographical order.
+Each element in the sequence is encoded by a u32le representing the number of bytes followed by the bytes themselves.
+
+See https://numcodecs.readthedocs.io/en/stable/other/vlen.html#vlenbytes for details about the encoding.
+
+## Change log
+
+No changes yet.
+
+## Current maintainers
+
+* [zarr-python core development team](https://github.com/orgs/zarr-developers/teams/python-core-devs)
diff --git a/codecs/vlen-bytes/schema.json b/codecs/vlen-bytes/schema.json
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+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "oneOf": [
+    {
+      "type": "object",
+      "properties": {
+        "name": {
+          "const": "vlen-bytes"
+        },
+        "configuration": {
+          "type": "object",
+          "additionalProperties": false
+        }
+      },
+      "required": ["name"],
+      "additionalProperties": false
+    },
+    { "const": "vlen-bytes" }
+  ]
+}
diff --git a/codecs/vlen-utf8/README.md b/codecs/vlen-utf8/README.md
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+# Vlen-utf8 codec
+
+Defines an `array -> bytes` codec that serializes variable-length UTF-8 string arrays.
+
+## Codec name
+
+The value of the `name` member in the codec object MUST be `vlen-utf8`.
+
+## Configuration parameters
+
+None.
+
+## Example
+
+For example, the array metadata below specifies that the array contains variable-length UTF-8 strings:
+
+```json
+{
+    "data_type": "string",
+    "codecs": [{
+        "name": "vlen-utf8"
+    }],
+}
+```
+
+## Format and algorithm
+
+This is a `array -> bytes` codec.
+
+This codec is only compatible with the [`"string"`](../../data-types/string/README.md) data type.
+
+In the encoded format, each chunk is prefixed with a 32-bit little-endian unsigned integer (u32le) that specifies the number of elements in the chunk.
+This prefix is followed by a sequence of encoded elements in lexicographical order.
+Each element in the sequence is encoded by a u32le representing the number of bytes followed by the bytes themselves.
+The bytes for each element are obtained by encoding the element as UTF8 bytes.
+
+See https://numcodecs.readthedocs.io/en/stable/other/vlen.html#vlenutf8 for details about the encoding.
+
+## Change log
+
+No changes yet.
+
+## Current maintainers
+
+* [zarr-python core development team](https://github.com/orgs/zarr-developers/teams/python-core-devs)
diff --git a/codecs/vlen-utf8/schema.json b/codecs/vlen-utf8/schema.json
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+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "oneOf": [
+    {
+      "type": "object",
+      "properties": {
+        "name": {
+          "const": "vlen-utf8"
+        },
+        "configuration": {
+          "type": "object",
+          "additionalProperties": false
+        }
+      },
+      "required": ["name"],
+      "additionalProperties": false
+    },
+    { "const": "vlen-utf8" }
+  ]
+}
diff --git a/data-types/bytes/README.md b/data-types/bytes/README.md
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+# Bytes data type
+
+Defines a data type for variable-length byte strings.
+
+## Permitted fill values
+
+The value of the `fill_value` metadata key must be an array of byte values.
+
+## Example
+
+For example, the array metadata below specifies that the array contains variable-length byte strings:
+
+```json
+{
+    "data_type": "bytes",
+    "fill_value": [1, 2, 3],
+    "codecs": [{
+        "name": "vlen-bytes"
+    }],
+}
+```
+
+## Notes
+
+Currently, this data type is only compatible with the [`"vlen-bytes"`](../../codecs/vlen-bytes/README.md) codec.
+
+## Change log
+
+No changes yet.
+
+## Current maintainers
+
+* [zarr-python core development team](https://github.com/orgs/zarr-developers/teams/python-core-devs)
diff --git a/data-types/bytes/schema.json b/data-types/bytes/schema.json
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+++ b/data-types/bytes/schema.json
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+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "oneOf": [
+    {
+      "type": "object",
+      "properties": {
+        "name": {
+          "const": "bytes"
+        },
+        "configuration": {
+          "type": "object",
+          "additionalProperties": false
+        }
+      },
+      "required": ["name"],
+      "additionalProperties": false
+    },
+    { "const": "bytes" }
+  ]
+}
diff --git a/data-types/string/README.md b/data-types/string/README.md
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+++ b/data-types/string/README.md
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+# String data type
+
+Defines a data type for variable-length UTF8 strings.
+
+## Permitted fill values
+
+The value of the `fill_value` metadata key must be unicode string.
+
+## Example
+
+For example, the array metadata below specifies that the array contains variable-length byte strings:
+
+```json
+{
+    "data_type": "string",
+    "fill_value": "foo",
+    "codecs": [{
+        "name": "vlen-utf8"
+    }],
+}
+```
+
+## Notes
+
+Currently, this data type is only compatible with the [`"vlen-utf8"`](../../codecs/vlen-utf8/README.md) codec.
+
+## Change log
+
+No changes yet.
+
+## Current maintainers
+
+* [zarr-python core development team](https://github.com/orgs/zarr-developers/teams/python-core-devs)
diff --git a/data-types/string/schema.json b/data-types/string/schema.json
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+++ b/data-types/string/schema.json
@@ -0,0 +1,20 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "oneOf": [
+    {
+      "type": "object",
+      "properties": {
+        "name": {
+          "const": "string"
+        },
+        "configuration": {
+          "type": "object",
+          "additionalProperties": false
+        }
+      },
+      "required": ["name"],
+      "additionalProperties": false
+    },
+    { "const": "string" }
+  ]
+}