diff --git a/edosl0util/rdrgen.py b/edosl0util/rdrgen.py
index 3ade43d77f92c4020a1ba7c4ee3c699d31607410..c40ec850e75bd9cc098b65a17b197dcf8fe73496 100644
--- a/edosl0util/rdrgen.py
+++ b/edosl0util/rdrgen.py
@@ -27,8 +27,13 @@ def packets_to_rdrs(sat, l0_files, **kwargs):
     build_rdr(sat, iter_pkts(l0_files), **kwargs)
 
 
-def build_rdr(sat, pkt_iter, output_dir='.', aggr_level=None, diary_cushion=10000000,
-              attr_overrides={}):
+def build_rdr(sat, pkt_iter, output_dir='.', aggr_type='idps', aggr_level=None,
+              diary_cushion=10000000, attr_overrides={}):
+    """Construct RDR file(s) from L0 packets
+
+    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).
     # divy packets up into temp files organized by granule
     file_mgr = BinnedTemporaryFileManager()
     get_jpss_packet_time = GetJpssPacketTime()
@@ -45,10 +50,22 @@ def build_rdr(sat, pkt_iter, output_dir='.', aggr_level=None, diary_cushion=1000
     rdr_types = set(rdr_type for rdr_type, gran_iet in gran_infos)
     primary_type, packaged_type = process_rdr_types(rdr_types, force_packaging=False)
     rdr_types = sorted(rdr_types, key=(lambda t: 1 if t is primary_type else 2))
-    aggr_level = aggr_level or primary_type.default_aggregation
-    primary_aggr_iets = sorted(set(
-        get_aggregate_start(sat, primary_type.gran_len, aggr_level, gran_iet)
-        for (rdr_type, gran_iet) in gran_infos if rdr_type is primary_type))
+    if aggr_type == 'idps':
+        aggr_level = aggr_level or primary_type.default_aggregation
+        primary_aggr_iets = sorted(set(
+            get_aggregate_start(sat, primary_type.gran_len, aggr_level, gran_iet)
+            for (rdr_type, gran_iet) in gran_infos if rdr_type is primary_type))
+    elif aggr_type == 'full':
+        # produce a single output file, ignoring IDPS-style aggregation boundaries
+        assert aggr_level is None
+        first_gran_iet = min(gran_iet for (rdr_type, gran_iet) in gran_infos
+                             if rdr_type is primary_type)
+        last_gran_iet = max(gran_iet for (rdr_type, gran_iet) in gran_infos
+                             if rdr_type is primary_type)
+        aggr_level = (last_gran_iet - first_gran_iet) / primary_type.gran_len + 1
+        primary_aggr_iets = [first_gran_iet]
+    else:
+        raise ValueError('aggr_type must be idps or input')
 
     # now generate the RDRs
     rdr_files = []
@@ -56,8 +73,7 @@ def build_rdr(sat, pkt_iter, output_dir='.', aggr_level=None, diary_cushion=1000
         rdr_writer = RdrWriter(sat, rdr_types, aggr_iet, aggr_level, output_dir,
                                **attr_overrides)
         rdr_writer.write_aggregate(primary_type, aggr_iet, aggr_level)
-        gran_iets = get_aggregate_granule_times(
-            sat, primary_type.gran_len, aggr_level, aggr_iet)
+        gran_iets = [aggr_iet + i * primary_type.gran_len for i in range(aggr_level)]
         for gran_iet in gran_iets:
             with file_mgr.process_file((primary_type, gran_iet)) as pkt_file:
                 pkts = list(jpss_packet_stream(pkt_file))