diff --git a/README.md b/README.md
line changes: +56/-2
index 38b6763..3f863b7
--- a/README.md
+++ b/README.md

@@ -78,6 +78,15 @@ identifier_bin_args = []
 
 # Skip files that have already been processed by pww
 #
+# If the pww-specific processed flag is set, which it is after pww process an
+# image unless `disable_pww_tag` is enabled or another application has stripped
+# it, the pww will skip processing the image again.
+#
+# In a pww-only workflow, this allows running pww repeatedly over a large set of
+# input files and skipping the ones that were processed in previous runs.
+# Unfortunately, other applications (e.g. Darktable) strip unknown tags on
+# import, so this might not work in mixed workflows.
+#
 skip_processed = false
 
 # Policy defining which file(s) should be updated with new metadata

@@ -225,6 +234,9 @@ forbidden_tags = []
 # pww sets an Xmp tag indicating it has processed a file.  This can be used to
 # skip reprocessing of files that have already been handled.
 #
+# Unfortunately, some applications (e.g. Darktable) delete unknown tags on
+# import, so this isn't necessarily useful.
+#
 disable_pww_tag = false
 ```
 

@@ -236,21 +248,63 @@ The command-line requires one or more paths to image files.  Some additional arg
 Usage: photo-what-what [OPTIONS] <IMAGE>...
 
 Arguments:
-  <IMAGE>...  Image files to analyze and tag
+  <IMAGE>...
+          Image files to analyze and tag
 
 Options:
   -b, --identifier-bin <IDENTIFIER_BIN>
           Path to program that classifies images
+
+      --temp-dir <TEMP_DIR>
+          Directory to store temporary files
+
   -n, --dry-run
           Do not actually write metadata to file, but print which files would have changed
+
+  -s, --skip-processed
+          Skip files that have already been processed by pww
+
+      --file-update-policy <FILE_UPDATE_POLICY>
+          Policy for which metadata should be updated
+
+          Possible values:
+          - display-only:                Just print the tags, do not update any files
+          - sidecar-only:                Only update XMP sidecar (error if XMP file missing).  Only
+            sidecar tags are used
+          - image-only:                  Only update image itself.  Only image tags are used
+          - sidecar-and-image:           Update both XMP sidecar and image itself.  Both sidecar and
+            image tags are used
+          - sidecar-if-present:          Only update XMP sidecar if present, otherwise update image
+            itself.  Either sidecar or image tags are used
+          - sidecar-unless-common-image: Only update XMP sidecar unless image is one of a few common
+            known types with good EXIF support (JPG, PNG, TIFF, WebP). Either sidecar or image tags
+            are used.  Error if XMP file missing
+
+      --tag-update-policy <TAG_UPDATE_POLICY>
+          Policy for how changes should be made to the specified tags
+
+          Possible values:
+          - replace:          Replace all existing contents (if any) with new items
+          - append:           Append new items to existing tag contents
+          - replace-prefixed: Remove existing items with the same prefix and then append new ones
+
   -v, --verbose
           Print information about which tags are written
+
   -d, --debug
           Print extra trace information about program flow, for debugging
+
+  -e, --halt-on-error
+          Whether to stop processing after first error, or continue
+
       --keep-converted
           Keep converted image files in temp directory instead of removing them
+
+      --disable-pww-tag
+          Disables setting of the pww processed metadata field
+
   -h, --help
-          Print help
+          Print help (see a summary with '-h')
 ```
 
 ## Dependencies