Index: trunk/doc/design/10_forge.html
===================================================================
--- trunk/doc/design/10_forge.html	(revision 5124)
+++ trunk/doc/design/10_forge.html	(revision 5125)
@@ -54,7 +54,7 @@
 <ul>
 	<li> <b>map</b>: on copy, an array is mapped into an array; on edit-in-place each array element is edited individually
 	<li> <b>atomic</b>: if array, the whole array is dealt with at once, as an atomic object; if scalar, result is a scalar too
-	<li> <b>darr</b>: if destination is an array, the source (or each element of the source, if it's an array) is combined into the destination array
+	<li> <b>darr</b>: if destination is an array, the source (or each element of the source, if it's an array) is combined into the destination array. Fails if source is array and destination is scalar.
 </ul>