diff --git a/edosl0util/rdrgen.py b/edosl0util/rdrgen.py
index c40ec850e75bd9cc098b65a17b197dcf8fe73496..61a827b7f6c18015cca3219f8317bcf1cd41346f 100644
--- a/edosl0util/rdrgen.py
+++ b/edosl0util/rdrgen.py
@@ -33,7 +33,13 @@ def build_rdr(sat, pkt_iter, output_dir='.', aggr_type='idps', aggr_level=None,
 
     Default aggregation behavior uses file boundaries computed in the same way
     as for IDPS assuming the default aggregation level depending on the instrument
-    (e.g. 85 sec for VIIRS, 8 min for CrIS).
+    (e.g. 85 sec for VIIRS, 8 min for CrIS). A different aggregation level can
+    be given as an integer number of granule (e.g. 4 to get roughly 5.5 min files
+    for VIIRS). Finally, aggr_type can be set to 'full' to request that a single
+    file gets produced (thus aggregating all granules containing the given
+    packets).
+    """
+
     # divy packets up into temp files organized by granule
     file_mgr = BinnedTemporaryFileManager()
     get_jpss_packet_time = GetJpssPacketTime()