add Compatibility section

Author: hugohn

bip-hugonguyen-bsms.mediawiki

@@ -180,6 +180,9 @@ For signers that use QR codes to transmit data, key and descriptor records can b
 
 Also refer to [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-015-account.md UR Type Definition for BIP44 Accounts] and [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-010-output-desc.md UR Type Definition for Bitcoin Output Descriptors] for more details.
 
+==Compatibility==
+To comply with this standard, a Signer must be able to persist the descriptor record in its storage. 
+
 ==Security==
 
 This proposal introduces two layers of protection. The first one is a temporary, secret <tt>TOKEN</tt>. The second one is the confirmation of the wallet's first address.