diff --git a/ch07_authorization-authentication.adoc b/ch07_authorization-authentication.adoc
index 79e3b9ab..3b7d1815 100644
--- a/ch07_authorization-authentication.adoc
+++ b/ch07_authorization-authentication.adoc
@@ -685,7 +685,7 @@ spent.
 === Data Recording Output (OP_RETURN)
 
 Bitcoin's
-distributed and timestamped blockchain has potential uses
+distributed ((("scripts", "OP_RETURN", id="script-op-return")))((("OP_RETURN scripts", id="op-return")))((("nonpayment data", id="nonpayment-data")))((("blockchain", "nonpayment data in", id="blockchain-nonpayment")))((("output scripts", "OP_RETURN", id="output-script-op-return")))and timestamped blockchain has potential uses
 beyond payments. Many developers have tried to use the transaction
 scripting language to take advantage of the security and resilience of
 the system for applications such as digital notary services.
@@ -749,7 +749,7 @@ will halt the execution of the validation script and mark the
 transaction as invalid. The execution of +OP_RETURN+ essentially causes the
 script to "RETURN" with a +FALSE+ and halt. Thus, if you accidentally
 reference an +OP_RETURN+ output as an input in a transaction, that
-transaction is invalid.
+transaction((("scripts", "OP_RETURN", startref="script-op-return")))((("OP_RETURN scripts", startref="op-return")))((("nonpayment data", startref="nonpayment-data")))((("blockchain", "nonpayment data in", startref="blockchain-nonpayment")))((("output scripts", "OP_RETURN", startref="output-script-op-return"))) is invalid.
 
 [[lock_time_limitations]]
 ==== Transaction Lock Time Limitations