diff --git a/TrimSP.html b/TrimSP.html
index 3f69d7c..35665ee 100644
--- a/TrimSP.html
+++ b/TrimSP.html
@@ -319,6 +319,9 @@
 	            <li value="1">Table 1 in Anderson & Ziegler (1977).</li>
 	            <li value="2">Table 3.1 in ICRU Report 49 (1993).</li>
 	            <li value="3">Table II in McFadden et al. (2023) and McFadden et al. (unpublished).</li>
+	          Note: While option 3 contains the most up-to-date values, it currently
+	          does not contain entries for every target element. For elements with
+	          missing data, values from option 2 are taken instead.
 	          </ol>
 	        </span>
 	      </td>