Specify procedure for new fields and versions

Author: achow101

bip-0174.mediawiki

@@ -479,6 +479,18 @@ Updaters and combiners that need to add a version number to a PSBT should use th
 For example, if a combiner sees two PSBTs for the same transaction, one with version 0, and the other with version 1, then it should combine them and produce a PSBT with version 1.
 If an updater is updating a PSBT and needs to add a field that is only available in version 1, then it should set the PSBT version number to 1 unless a version higher than that is already specified.
 
+===Procedure For New Fields===
+
+New fields should first be proposed on the bitcoin-dev mailing list.
+If a field requires significatn description as to its usage, it should be accompanied by a separate BIP.
+The field must be added to the field listing tables in the Specification section.
+
+===Procedure For New Versions===
+
+New PSBT versions must be described in a separate BIP.
+The BIP may reference this BIP and any components of PSBT version 0 that are retained in the new version.
+Any new fields described in the new version must be added to the field listing tables in the Specification section.
+
 ==Compatibility==
 
 This transaction format is designed so that it is unable to be properly unserialized