diff --git a/CIP-????/cddl/version_1.cddl b/CIP-????/cddl/version_1.cddl
new file mode 100644
index 0000000000..8126221444
--- /dev/null
+++ b/CIP-????/cddl/version_1.cddl
@@ -0,0 +1,153 @@
+; "????" to be replaced by the CIP number, as a `uint`.
+metadata = { ???? => action }
+
+; =========================================================================
+; CIP-???? actions
+
+action =
+  {
+    ? assign_metadata_oracle : action_oracle,
+    ? simple_metadata_update : action_simple,
+    ? regex_metadata_update : action_regex,
+    ? tabular_metadata_update : action_tabular
+  }
+
+action_oracle = { * policy_id => oracle_assignment }
+
+oracle_assignment =
+  {
+    ? main_address : address,
+    ? update_address : address
+  }
+
+action_simple = { * policy_id => { * asset_name => metadata_details } }
+
+action_regex = { * policy_id => { * asset_regex => metadata_details } }
+
+action_tabular = { * policy_id => csv_update_opaque }
+
+; Technically, both policy IDs and asset names should be 32 bytes long.
+; However, this isn't enforced for asset names, and CIP-25v1 already treats
+; these as `text_64`, so we don't enforce the more narrow `bytes_32` type
+; here.
+policy_id = text_64
+asset_name = text_64
+
+asset_regex = text_regex_extendable
+
+; =========================================================================
+; Backwards compatibility with CIP-25 (simple and regex metadata updates)
+; Definitions for the following fields in `metadata_details` should follow
+; the same schema as in CIP-25, except that `name` and `image` are optional.
+; Other fields can have arbitrary `transaction_metadatum` values.
+metadata_details =
+  {
+    ? name : text_64,
+    ? image : text_extendable,
+    ? mediaType : text_64,
+    ? description : text_extendable,
+    ? files : [* files_details],
+    * ( label_64 => transaction_metadatum )
+  }
+
+files_details =
+  {
+    name : text_64,
+    mediaType : text_64,
+    src : text_extendable
+  }
+
+; =========================================================================
+; Tabular updates' CSV schema
+
+; Cardano ledger imposes a fixed size of 64 on text and bytestrings,
+; which prevents us from directly encoding a CSV table as a single long
+; text. This means that, formally, the CSV in a tabular update
+; is just an opaque extendable text (i.e. a fixed text or an array of fixed 
+; texts).
+csv_update_opaque = text_extendable
+
+; Informally, if we concatenate the `csv_update_opaque` value to a single long
+; text, and then split it on unescaped newline characters, then it should comply
+; with the following cddl schema.
+; (Newline characters inside of a double-quoted field value are considered
+; escaped, which means that they do no indicate the start of a new record.)
+csv_update = [ header, * record ]
+header = [ "tokenName", * header_field ]
+record = [ text_64, * record_field ]
+header_field = text
+record_field = text
+
+; For a given `policy_id`, a `csv_update` value can be transformed into a
+; `metadata_details` value as follows:
+; 1. Pair each `record_field` with its corresponding `header_field`
+;    (i.e. like zipping two lists).
+; 2. Transform each `header_field` into a `[header_field_part]` array, by
+;    splitting it on the '.' character.
+; 3. For each pair of `record_field` and `[header_field_part]` values, construct
+;    the following nested object:
+;      csv_nested_object = 
+;        { header_field_part[0] =>
+;          { header_field_part[1] =>
+;            { header_field_part[2] =>
+;              ...
+;                        { header_field_part[N] => `record_field` }
+;              ...
+;            }
+;          }
+;        }
+; 4. For each record, combine and normalize its record fields' constructed
+;    nested objects into a single unified object for that record. Nest the
+;    unified object under the record's "tokenName" value:
+;      csv_record_object = { text_64 => Union([csv_nested_object]) }
+; 5. Unify the `record_object`s into a single object, and then nest it under
+;    the `policy_id`:
+;      csv_policy_object = { policy_id => Union([csv_record_object]) }
+; 6. Combine the `action_simple_single` values into a single `action_simple`
+;    value:
+;      csv_update_simple = Union([csv_policy_object])
+;
+; The effect of a `csv_update_opaque` on the token metadata state in the
+; CIP-???? indexer must be the same as the effect of the corresponding
+; `csv_update_simple` (applied as a simple update action).
+
+; =========================================================================
+; Imported from cardano-ledger/.../babbage.cddl
+transaction_metadatum =
+    { * transaction_metadatum => transaction_metadatum }
+  / [ * transaction_metadatum ]
+  / int
+  / bytes_64
+  / text_64
+
+address = bytes
+
+; =========================================================================
+; Convenient type aliases
+
+; Fixed-size text and bytes
+label_32 = bytes_32 / text_32
+bytes_32 = bytes .size (0..32)
+text_32 = text .size (0..32)
+
+label_64 = bytes_64 / text_64
+bytes_64 = bytes .size (0..64)
+text_64 = text .size (0..64)
+
+; Extendable text and bytes
+text_extendable = text_64 / [ * text_64 ]
+bytes_extendable = bytes_64 / [ * bytes 64 ]
+
+; Regex (fixed-size)
+; Tag 35 is for regular expressions in Perl Compatible Regular
+; Expressions (PCRE) / JavaScript syntax [ECMA262].
+; https://www.rfc-editor.org/rfc/rfc7049#section-2.4.4.3
+; https://www.ecma-international.org/publications-and-standards/standards/ecma-262/
+text_regex = #6.35(text_64)
+
+; Regex (extendable size)
+; Technically, CBOR maps can have arrays as keys. This prevents them from being
+; directly convertable to JSON, but we can recover JSON-convertability by
+; concatenating the array-valued key into a single UTF-8 text.
+; The resulting concatenated text should be interpreted as `#6.35(text)`.
+text_regex_extendable = text_extendable
diff --git a/CIP-????/cddl/version_2.cddl b/CIP-????/cddl/version_2.cddl
new file mode 100644
index 0000000000..99e7eb15a1
--- /dev/null
+++ b/CIP-????/cddl/version_2.cddl
@@ -0,0 +1,85 @@
+; "????" to be replaced by the CIP number, as a `uint`.
+metadata = { ???? => action }
+
+; =========================================================================
+; CIP-???? actions
+
+; When version 2 mode is enabled for a CIP-???? action, all `policy_id` and
+; `asset_name` values are interpreted as `bytes_64`, similar to CIP-25v2.
+action =
+  {
+    version = 2,
+    ? assign_metadata_oracle : action_oracle,
+    ? simple_metadata_update : action_simple,
+  }
+
+; Regex and tabular updates are disallowed in version 2, because it is unclear
+; how to apply regular expressions to non-UTF-8 bytestrings (or their
+; corresponding hex encodings) and it is unclear how to embed raw bytestrings
+; in CSV.
+
+action_oracle = { * policy_id => oracle_assignment }
+
+oracle_assignment =
+  {
+    ? main_address : address,
+    ? update_address : address
+  }
+
+action_simple = { * policy_id => { * asset_name => metadata_details } }
+
+; Technically, both policy IDs and asset names should be 32 bytes long.
+; However, this isn't enforced for asset names, and CIP-25v2 already treats
+; these as `bytes_64`, so we don't enforce the more narrow `bytes_32` type
+; here.
+policy_id = bytes_64
+asset_name = bytes_64
+
+; =========================================================================
+; Backwards compatibility with CIP-25 (simple and regex metadata updates)
+; Definitions for the following fields in `metadata_details` should follow
+; the same schema as in CIP-25, except that `name` and `image` are optional.
+; Other fields can have arbitrary `transaction_metadatum` values.
+metadata_details =
+  {
+    ? name : text_64,
+    ? image : text_extendable,
+    ? mediaType : text_64,
+    ? description : text_extendable,
+    ? files : [* files_details],
+    * ( label_64 => transaction_metadatum )
+  }
+
+files_details =
+  {
+    name : text_64,
+    mediaType : text_64,
+    src : text_extendable
+  }
+
+; =========================================================================
+; Imported from cardano-ledger/.../babbage.cddl
+transaction_metadatum =
+    { * transaction_metadatum => transaction_metadatum }
+  / [ * transaction_metadatum ]
+  / int
+  / bytes_64
+  / text_64
+
+address = bytes
+
+; =========================================================================
+; Convenient type aliases
+
+; Fixed-size text and bytes
+label_32 = bytes_32 / text_32
+bytes_32 = bytes .size (0..32)
+text_32 = text .size (0..32)
+
+label_64 = bytes_64 / text_64
+bytes_64 = bytes .size (0..64)
+text_64 = text .size (0..64)
+
+; Extendable text and bytes
+text_extendable = text_64 / [ * text_64 ]
+bytes_extendable = bytes_64 / [ * bytes 64 ]