diff --git a/tools/buildman/README b/tools/buildman/README
index aaf0a10..d4e8404 100644
--- a/tools/buildman/README
+++ b/tools/buildman/README
@@ -108,6 +108,15 @@
 * '^tegra[23]0$' All boards with either Tegra20 or Tegra30 SoC
 * 'powerpc'      All PowerPC boards
 
+While the default is to OR the terms together, you can also make use of
+the '&' operator to limit the selection:
+
+* 'freescale & arm sandbox'  All Freescale boards with ARM architecture,
+                             plus sandbox
+
+It is convenient to use the -n option to see whaat will be built based on
+the subset given.
+
 Buildman does not store intermediate object files. It optionally copies
 the binary output into a directory when a build is successful. Size
 information is always recorded. It needs a fair bit of disk space to work,