--- a/function-reference/install-functions/text.xml	
+++ a/function-reference/install-functions/text.xml	
@@ -102,7 +102,8 @@ the first is the source name, the second the name to use when installing.
       <c>dodir</c>
     </ti>
     <ti>
-      Install a directory
+      Install a directory that can be removed by a package unmerge when any package that owns it
+      has been unmerged and it is empty.
     </ti>
   </tr>
   <tr>
@@ -246,7 +247,9 @@ the first is the source name, the second the name to use when installing.
       <c>keepdir</c>
     </ti>
     <ti>
-      Create a directory with an empty <c>.keep</c> file in it.
+      Install a directory, typically used to store configuration or generated runtime data,
+      that can be removed by a package unmerge only when all other
+      packages that own it have been unmerged and it is empty.
     </ti>
   </tr>
   <tr>