Update CommandLineSyntax.md

CommandLineSyntax.md

@@ -39,28 +39,43 @@ special commands for VCDIFF inputs:
     printdelta  print information about the entire delta
     printhdr    print information about the first window
     printhdrs   print information about all windows
+    recode      encode with new application/secondary settings
+    merge       merge VCDIFF inputs (see below)
+merge patches:
+
+  xdelta3 merge -m 1.vcdiff -m 2.vcdiff 3.vcdiff merged.vcdiff
+
 standard options:
    -0 .. -9     compression level
    -c           use stdout
    -d           decompress
    -e           compress
-   -f           force overwrite
+   -f           force (overwrite, ignore trailing garbage)
+   -F           force the external-compression subprocess
    -h           show help
    -q           be quiet
    -v           be verbose (max 2)
    -V           show version
 memory options:
    -B bytes     source window size
    -W bytes     input window size
+   -P size      compression duplicates window
+   -I size      instruction buffer size (0 = unlimited)
 compression options:
    -s source    source file to copy from (if any)
-   -S [djw|fgk] enable/disable secondary compression
+   -S [lzma|djw|fgk|none] enable/disable secondary compression
    -N           disable small string-matching compression
    -D           disable external decompression (encode/decode)
    -R           disable external recompression (decode)
    -n           disable checksum (encode/decode)
    -C           soft config (encode, undocumented)
    -A [apphead] disable/provide application header (encode)
+   -J           disable output (check/compute only)
+   -m           arguments for "merge"
+the XDELTA environment variable may contain extra args:
+   XDELTA="-s source-x.y.tar.gz" \
+   tar --use-compress-program=xdelta3 \
+       -cf target-x.z.tar.gz.vcdiff target-x.y
 ```
 
-The `-A` flag may be used to set application-specific data in the VCDIFF header (you may view with `xdelta3 printhdr`). By default, the application-specific data includes the source and input filenames, as well as descriptors to help with ExternalCompression. You can disable the application header with `-A=`.
+The `-A` flag may be used to set application-specific data in the VCDIFF header (you may view with `xdelta3 printhdr`). By default, the application-specific data includes the source and input filenames, as well as descriptors to help with ExternalCompression. You can disable the application header with `-A=`.