diff --git a/base_classes/NXdata.nxdl.xml b/base_classes/NXdata.nxdl.xml
index f2431e371..a232ac3b4 100644
--- a/base_classes/NXdata.nxdl.xml
+++ b/base_classes/NXdata.nxdl.xml
@@ -115,12 +115,12 @@
 			the axes attribute can be omitted.
 		</doc>
 	</attribute>
-	<attribute name="default_slice" type="NX_CHAR">
+	<attribute name="default_slice" type="NX_CHAR_OR_NUMBER">
 		<doc>
 			Which slice of data to show in a plot by default. This is useful especially for
 			datasets with more than 2 dimensions.
 
-			Should be an array of strings of length equal to the number of dimensions
+			Should be an array of length equal to the number of dimensions
 			in the data, with the following possible values:
 
 			* ".": All the data in this dimension should be included