From 66d3aea286d4859d874ad65f72e3b1a53e55f5f8 Mon Sep 17 00:00:00 2001
From: tristan-bp <150206045+tristan-bp@users.noreply.github.com>
Date: Thu, 6 Nov 2025 22:13:25 -0600
Subject: [PATCH] expanding charset to include underscores

---
 CAIPs/caip-10.md |  7 ++++---
 CAIPs/caip-19.md | 11 ++++++-----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/CAIPs/caip-10.md b/CAIPs/caip-10.md
index e33882e5..fee3a75a 100644
--- a/CAIPs/caip-10.md
+++ b/CAIPs/caip-10.md
@@ -6,7 +6,7 @@ discussions-to: https://github.com/ChainAgnostic/CAIPs/pull/10
 status: Final
 type: Standard
 created: 2020-03-13
-updated: 2022-10-23
+updated: 2025-11-06
 requires: 2
 ---
 
@@ -45,10 +45,10 @@ The `account_id` is a case-sensitive string in the form
 ```
 account_id:        chain_id + ":" + account_address
 chain_id:          [-a-z0-9]{3,8}:[-_a-zA-Z0-9]{1,32} (See [CAIP-2][])
-account_address:   [-.%a-zA-Z0-9]{1,128}
+account_address:   [-_.%a-zA-Z0-9]{1,128}
 ```
 
-Note that `-`, `%` and `.` characters are allowed, but no other
+Note that `-`, `_`, `%` and `.` characters are allowed, but no other
 non-alphanumerics such as `:`, `/` or `\`.  Implementers are recommended to use
 "URL encoding" (% + 2-character codes, canonically capitalized) as per [Section
 2][rfc3986sec2.1] of [RFC 3986][rfc3986] to escape any further non-alphanumeric
@@ -125,6 +125,7 @@ of specification for details.
 
 ## Changelog
 
+- 2025-11-06: expanded charset to include `_`
 - 2022-10-23: expanded charset to include `-`,`.`, and `%`; also added
   canonicalization section and links
 - 2022-03-10: update RegEx to incorporate CAIP-2 reference
diff --git a/CAIPs/caip-19.md b/CAIPs/caip-19.md
index 41482a0e..da448736 100644
--- a/CAIPs/caip-19.md
+++ b/CAIPs/caip-19.md
@@ -6,7 +6,7 @@ discussions-to: https://github.com/ChainAgnostic/CAIPs/pull/19
 status: Review
 type: Standard
 created: 2020-06-23
-updated: 2020-06-23
+updated: 2025-11-06
 requires: 2
 ---
 
@@ -46,10 +46,10 @@ The `asset_type` is a case-sensitive string in the form
 asset_type:        chain_id + "/" + asset_namespace + ":" + asset_reference
 chain_id:          Namespace+Blockchain ID as per [CAIP-2][]
 asset_namespace:   [-a-z0-9]{3,8}
-asset_reference:   [-.%a-zA-Z0-9]{1,128}
+asset_reference:   [-_.%a-zA-Z0-9]{1,128}
 ```
 
-Note that `-`, `%` and `.` characters are allowed in `asset_references`, which
+Note that `-`, `_`, `%` and `.` characters are allowed in `asset_references`, which
 include on-chain addresses like those specified in [CAIP-10][], but no other
 non-alphanumerics such as `:`, `/` or `\`.  Implementers are recommended to use
 "URL encoding" (% + 2-character codes, canonically capitalized) as per [Section
@@ -73,11 +73,11 @@ The `asset_id` is a case-sensitive string in the form
 
 ```
 asset_id:    asset_type + "/" + token_id 
-token_id:   [-.%a-zA-Z0-9]{1,78}
+token_id:   [-_.%a-zA-Z0-9]{1,78}
 
 ```
 
-Note that `-`, `%` and `.` characters are allowed, but no other
+Note that `-`, `_`, `%` and `.` characters are allowed, but no other
 non-alphanumerics such as `:`, `/` or `\`.  Implementers are recommended to use
 "URL encoding" (% + 2-character codes, canonically capitalized) as per [Section
 2][rfc3986sec2.1] of [RFC 3986][rfc3986] to escape any further non-alphanumeric
@@ -173,6 +173,7 @@ hedera:mainnet/nft:0.0.55492/12
 
 ## Changelog
 
+- 2025-11-06: expanded charset to include `_`
 - 2022-10-23: 
     - expanded charset to include `-`,`.`, and `%`
     - added canonicalization section and links