+./build/config.<pldistro>/yumexclude.pkgs
+ describe the set of node packages that are produced by the myplc build
+ and thus should be excluded from the stock fedora repos
+
+=== extensions
+as of this writing extensions are managed as follows:
+- at node installation, the tarball produced from nodeimage.pkgs is
+downloaded and untared to produce the node root filesystem
+- then we attempt to install an extension corresponding to each of the
+extensions that the node has in its 'extensions' tag
+- the first method is to try and download a tarball named after the
+extension. such tarballs are produced by the build from a .pkgs file,
+see above
+- if that fails, then the extension install is attempted through a
+ yum groupinstall extension<nodegroup>
+