BIP 21: Precisely define the valid query characters

bip-0021.mediawiki

@@ -41,10 +41,12 @@ Elements of the query component may contain characters outside the valid range.
  bitcoinparams  = bitcoinparam [ "&" bitcoinparams ]
  bitcoinparam   = amountparam | labelparam | messageparam | otherparam | reqparam
  amountparam    = "amount=" *digit [ "." *digit ]
- labelparam     = "label=" *pchar
- messageparam   = "message=" *pchar
- otherparam     = pchar *pchar "=" *pchar
- reqparam       = "req-" pchar *pchar "=" *pchar
+ labelparam     = "label=" *qchar
+ messageparam   = "message=" *qchar
+ otherparam     = qchar *qchar "=" *qchar
+ reqparam       = "req-" qchar *qchar "=" *qchar
+
+Here, "qchar" corresponds to valid characters of an RFC 3986 URI query component, excluding the "=" and "&" characters, which this BIP takes as separators.
 
 === Query Keys ===