--- a/doc-src/System/Thy/Sessions.thy Sun Aug 05 20:11:32 2012 +0200
+++ b/doc-src/System/Thy/Sessions.thy Sun Aug 05 21:57:25 2012 +0200
@@ -197,6 +197,13 @@
command line. Each such directory may contain a session
\texttt{ROOT} file with several session specifications.
+ Any session root directory may refer recursively to further
+ directories of the same kind, by listing them in a catalog file
+ @{verbatim "ROOTS"} line-by-line. This helps to organize large
+ collections of session specifications, or to make @{verbatim "-d"}
+ command line options persistent (say within @{verbatim
+ "$ISABELLE_HOME_USER/ROOTS"}).
+
\medskip The subset of sessions to be managed is determined via
individual @{text "SESSIONS"} given as command-line arguments, or
session groups that are given via one or more options @{verbatim