m7 op return update

This has been right in the code, but I kept forgetting to update the BIP.

Author: psztorc

bip-blind-merged-mining.mediawiki

@@ -85,12 +85,12 @@ Mainchain nodes are going to need this data later, so it must be easy to find. W
 
 ==== M7 -- "Blind-Mine the Sidechain(s)" ====
 
-Thus, (for n sidechains) we have a coinbase output with:
+Thus, (for n sidechains) we have a coinbase output with multiple OP_RETURNs (we've changed the tx-standardness policy to allow multiple OP_RETURNs):
 
     1-byte - OP_RETURN (0x6a)
-    1-byte - Push the following (4+(n*35)) bytes (0x??)
+    1-byte - Push the following 39 bytes (0x27)
     4-byte - Message header (0xD3407053)
-    (n*(32+5))-byte - A sequence of bytes, of the three Mini-Header items (h*, prevBlockRef, ChainIndex).
+    37-byte - A sequence of bytes, of the three Mini-Header items (h*, prevBlockRef, ChainIndex).
 
 ( We assume that 5 bytes are used for the Critical Data bytes (non h* parts of the Sidechain Mini-Header). For 256 sidechains, a total of 9,478 bytes [1+1+4+256\*(32+5)] are required, conveniently just below the 10 KB scriptPubKey size limit.)