diff --git a/amqp-format.md b/amqp-format.md
index c3c7a0318..c3b6be131 100644
--- a/amqp-format.md
+++ b/amqp-format.md
@@ -58,9 +58,9 @@ exceptions noted below.
 | String        | [string][amqp-string]       |
 | Integer       | [long][amqp-long]           |
 | Binary        | [binary][amqp-binary]       |
+| URI           | [string][amqp-string]       |
 | URI-reference | [string][amqp-string]       |
 | Timestamp     | [timestamp][amqp-timestamp] |
-| Map           | [map][amqp-map]             |
 | Any           | See 2.3.                    |
 
 A CloudEvents AMQP format implementation MUST allow for attribute values to be
diff --git a/avro-format.md b/avro-format.md
index 6ad9711ed..d151d66c0 100644
--- a/avro-format.md
+++ b/avro-format.md
@@ -50,7 +50,7 @@ The CloudEvents type system MUST be mapped to Avro types as follows.
 | Integer       | [int][avro-primitives]                                                 |
 | String        | [string][avro-primitives]                                              |
 | Binary        | [bytes][avro-primitives]                                               |
-| Map           | [map][avro-primitives]                                                 |
+| URI           | [string][avro-primitives] following [RFC 3986 §4.3][rfc3986-section43] |
 | URI-reference | [string][avro-primitives] following [RFC 3986 §4.1][rfc3986-section41] |
 | Timestamp     | [string][avro-primitives] following [RFC 3339][rfc3339] (ISO 8601)     |
 | Any           | See [2.2](#22-mapping-any-typed-attributes)                            |
@@ -163,4 +163,5 @@ The following table shows exemplary mappings:
 
 [rfc2119]: https://tools.ietf.org/html/rfc2119
 [rfc3986-section41]: https://tools.ietf.org/html/rfc3986#section-4.1
+[rfc3986-section43]: https://tools.ietf.org/html/rfc3986#section-4.3
 [rfc3339]: https://tools.ietf.org/html/rfc3339
diff --git a/json-format.md b/json-format.md
index 3cedfc1c8..8db364844 100644
--- a/json-format.md
+++ b/json-format.md
@@ -66,9 +66,9 @@ with exceptions noted below.
 | String        | [string][json-string]                                          |
 | Integer       | [number][json-number], only the `int` component is permitted   |
 | Binary        | [string][json-string], [Base64-encoded][base64] binary         |
+| URI           | [string][json-string] following [RFC 3986][rfc3986]            |
 | URI-reference | [string][json-string] following [RFC 3986][rfc3986]            |
 | Timestamp     | [string][json-string] following [RFC 3339][rfc3339] (ISO 8601) |
-| Map           | [JSON object][json-object]                                     |
 | Any           | [JSON value][json-value]                                       |
 
 Extension specifications MAY define diverging mapping rules for the values of
diff --git a/protobuf-format.md b/protobuf-format.md
index 57cfb7570..f4f41ed1d 100644
--- a/protobuf-format.md
+++ b/protobuf-format.md
@@ -74,9 +74,9 @@ follows:
 | ------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
 | String        | string_value                                                                                                                                |
 | Binary        | binary_value                                                                                                                                |
+| URI           | string_value (string expression conforming to URI-reference as defined in [RFC 3986 §4.3](https://tools.ietf.org/html/rfc3986#section-4.3)) |
 | URI-reference | string_value (string expression conforming to URI-reference as defined in [RFC 3986 §4.1](https://tools.ietf.org/html/rfc3986#section-4.1)) |
 | Timestamp     | string_value (string expression as defined in [RFC 3339](https://tools.ietf.org/html/rfc3339))                                              |
-| Map           | map_value                                                                                                                                   |
 | Integer       | int_value                                                                                                                                   |
 | Any           | Not applicable. Any is the enclosing CloudEventAny message itself                                                                           |
 
diff --git a/spec.md b/spec.md
index 9722fe4e6..aaf8822c9 100644
--- a/spec.md
+++ b/spec.md
@@ -155,6 +155,8 @@ These attributes, while descriptive of the event, are designed such that they
 can be serialized independent of the event data. This allows for them to be
 inspected at the destination without having to deserialize the event data.
 
+### Type System
+
 The following abstract data types are available for use in attributes. Each of
 these types MAY be represented differently by different event formats and in
 transport metadata fields. This specification defines a canonical