diff --git a/bip-xchgrate.mediawiki b/bip-xchgrate.mediawiki
index e3179c89..4524f156 100644
--- a/bip-xchgrate.mediawiki
+++ b/bip-xchgrate.mediawiki
@@ -35,6 +35,8 @@ Currency code(s) used herein are defined as such:
 * XBT is defined as 100000000 satoshis (commonly known as 1 BTC).
 * Strings longer than 3 characters may be used for currencies without an applicable code. (If a shorter code is desired despite this, it may be padded with space(s) to the left until it is 4 characters. Software MAY strip these spaces.)
 
+Rate is defined as: <code>primaryCurrencyValue / rate = secondaryCurrencyValue</code>
+
 ===Enumerating supported currency-pair tokens===
 
 Parameters: