diff --git a/spec/20-http_header_format.md b/spec/20-http_header_format.md
index 91f4aa2..a7f6b92 100644
--- a/spec/20-http_header_format.md
+++ b/spec/20-http_header_format.md
@@ -100,14 +100,18 @@ trace-flags      = 2HEXDIGLC   ; 8 bit flags. Currently, only one bit is used. S
 
 #### trace-id
 
-This is the ID of the whole trace forest and is used to uniquely identify a <a href="#dfn-distributed-traces">distributed trace</a> through a system. It is represented as a 16-byte array, for example, `4bf92f3577b34da6a3ce929d0e0e4736`. All bytes as zero (`00000000000000000000000000000000`) is considered an invalid value.
+This is the ID that is used to uniquely identify a <a href="#dfn-distributed-traces">distributed trace</a> through a system. It is represented as a 16-byte array, for example, `4bf92f3577b34da6a3ce929d0e0e4736`.
 
-If the `trace-id` value is invalid (for example if it contains non-allowed characters or all zeros), vendors MUST ignore the `traceparent`.
+For the interoperability between vendors, the 6 right most bytes of `trace-id` SHOULD be generated using random or pseudo-random number generation algorithm. If [[!RFC4122]] is used, only the <a data-cite='!RFC4122##section-4.4'>Algorithms for Creating a UUID from Truly Random or Pseudo-Random Numbers</a> can be used for `trace-id` value generation to satisfy the randomness requirement.
 
 See [considerations for trace-id field
 generation](#considerations-for-trace-id-field-generation) for recommendations
 on how to operate with `trace-id`.
 
+All bytes as zero (`00000000000000000000000000000000`) is considered an invalid value.
+
+If the `trace-id` value is invalid (for example if it contains non-allowed characters or all zeros), vendors MUST ignore the `traceparent`.
+
 #### parent-id
 
 This is the ID of this request as known by the caller (in some tracing systems, this is known as the `span-id`, where a `span` is the execution of a client request). It is represented as an 8-byte array, for example, `00f067aa0ba902b7`. All bytes as zero (`0000000000000000`) is considered an invalid value.
diff --git a/spec/60-trace-id-format.md b/spec/60-trace-id-format.md
index 204b735..aa1decb 100644
--- a/spec/60-trace-id-format.md
+++ b/spec/60-trace-id-format.md
@@ -6,7 +6,7 @@ practices will ensure better interoperability of different systems.
 
 ### Uniqueness of `trace-id`
 
-The value of `trace-id` SHOULD be globally unique. This field is typically used
+The value of `trace-id` SHOULD be globally unique. This field is used
 for unique identification of a <a>distributed trace</a>. It is common for
 <a>distributed traces</a> to span various components, including, for example,
 cloud services. Cloud services tend to serve variety of clients and have a very
@@ -15,16 +15,19 @@ even when local uniqueness might seem like a good solution.
 
 ### Randomness of `trace-id`
 
-Randomly generated value of `trace-id` SHOULD be preferred over other
-algorithms of generating a globally unique identifiers. Randomness of `trace-id`
-addresses some [security](#security-considerations) and [privacy
-concerns](#privacy-considerations) of exposing unwanted information. Randomness
-also allows tracing vendors to base sampling decisions on `trace-id` field value
-and avoid propagating an additional sampling context.
+For the interoperability between vendors, `trace-id` value SHOULD contain
+random bytes. With other considerations, random bytes SHOULD be the right most
+characters and at least 6 right most bytes (12 characters) SHOULD be generated
+using random or pseudo-random number generation algorithm.
 
-As shown in the next section, it is important for `trace-id` to carry
-"uniqueness" and "randomness" in the right part of the `trace-id`, for better
-inter-operability with some existing systems.
+Randomness of `trace-id` addresses some [security](#security-considerations)
+and [privacy concerns](#privacy-considerations) of exposing unwanted
+information. Randomness also allows tracing vendors to base various sharding
+and sampling decisions on `trace-id` field value and avoid propagating an
+additional sampling context.
+
+When [[!RFC4122]] is used for `trace-id` value generation, the required 12
+right most characters are generated as random or pseudo-random. Whenever possible fully randomly generated value of `trace-id` SHOULD be preferred.
 
 ### Handling `trace-id` for compliant platforms with shorter internal identifiers