diff --git a/bin/gatherstats.pl b/bin/gatherstats.pl
index 6118a70..b9070af 100755
--- a/bin/gatherstats.pl
+++ b/bin/gatherstats.pl
@@ -549,10 +549,12 @@ Newsgroups not found in the checkgroups file will be dropped (and
 logged to STDERR), and newsgroups found there but having no postings
 will be added with a count of 0 (and logged to STDERR).
 
-=item B<--hierarchy> I<TLH> (newsgroup hierarchy)
+=item B<--hierarchy> I<TLH> (newsgroup hierarchy/hierarchies)
 
 Override I<TLH> from F<newsstats.conf>.
 
+I<TLH> can be a single word or a comma-separated list.
+
 =item B<--rawdb> I<table> (raw data table)
 
 Override I<DBTableRaw> from F<newsstats.conf>.
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 3f46f78..a3de323 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -2,6 +2,7 @@ NewsStats 0.4.0 (unreleased)
   * Reformat $Conf{TLH} for GroupStats only.
   * Extract TLH check from HostStats to subroutine, fix no-op check.
   * Extract getting raw headers from HostStats to subroutine.
+  * Improve documentation for config file.
 
 NewsStats 0.3.0 (2025-05-18)
   * Extract GroupStats (in gatherstats) to subroutine.
diff --git a/doc/INSTALL b/doc/INSTALL
index 2ef057e..9a37207 100644
--- a/doc/INSTALL
+++ b/doc/INSTALL
@@ -62,8 +62,9 @@ INSTALLATION INSTRUCTIONS
 
    b) Optional configuration options
 
-   * TLH = de
-     Limit examination to that top-level hierarchy.
+   * TLH = de.alt,news.admin
+     Limit examination to that top-level hierarchy/hierarchies.
+     Comma-separated list.
 
 3) Database (mysql) setup
 
diff --git a/etc/newsstats.conf.sample b/etc/newsstats.conf.sample
index a960644..1ea3430 100644
--- a/etc/newsstats.conf.sample
+++ b/etc/newsstats.conf.sample
@@ -16,4 +16,6 @@ DBTableHosts = hosts_de
 #DBTableClnts =
 
 ### hierarchy configuration
+# comma-separated list of TLHs to parse
+# newsgroups not starting with one of those patterns are not counted
 TLH = de