readme changes

README.md

-# EdosL0Util
+# EdosL0Util (BETA)
 Tools for mangling EDOS L0 PDS files.
 
 ### Features:
 
-    * API for streaming packets
-    * CLI tools for:
-        - merging multiple PDS files
-        - splitting pds into X minute files
-        - truncating files to specified time range
-        - inspecting PDS info
-    * Dumping JPSS H5 RDRs to L0 PDS files
+* API for streaming packets
+* CLI tools for:
+    - merging multiple PDS files
+    - splitting pds into X minute files
+    - truncating files to specified time range
+    - inspecting PDS info
+* Dumping JPSS H5 RDRs to L0 PDS files for VIIRS, CrIS, and ATMS
+
+There is also support for creating a packet stream from Aqua L0 PDS files, but
+it has not been tested much. Most functionallity assumes EDOS L0 PDS files.
 
 
 ### Packet streaming
@@ -81,5 +84,25 @@ L0 PDS files.
     * rdr2l0
 
 
+### Creating L0 PDS Files from RDRs
+The ``rdr2l0`` tool will dump out an RDR in an order not suitable for use as a
+NASA L0 PDS file. To generate a L0 PDS file actually requires 2 steps:
+```
+$> rdr2l0 --diary --skipfill RNSCA-RVIRS_npp_d20151018_t2359214_e0000467_b20595_c20151019015559980487_noaa_ops.h5
+$> edosl0merge -o out.pds RNSCA-RVIRS_npp_d20151018_t2359214_e0000467_b20595_c20151019015559980487_noaa_ops.h5.science.pds
+```
+The resulting file ``out.pds`` will have packets sorted by time and apid with
+any duplicates removed.
+
+The typical case would be to dump multiple RDR files to pds then merge the 
+resulting PDS files into a 6 minute granule like so:
+```
+$> rdr2l0 --diary --skipfill RNSCA-RVIRS_npp_d20151018_t000*.h5
+$> edosl0merge -o out.pds --trunc_to "2015-10-18 00:00:00,2015-10-18 00:06:00" *.science.pds 
+```
+Which will create a proper 6 minute NASA L0 PDS file with any fill packets
+filtered out.
+
+
 If you have quesions or comments related to this software contac
 brucef@ssec.wisc.edu.