+When a directory is excluded, all its contents and sub-contents are also
+excluded. The sender doesn't scan through any of it at all, which can save a
+lot of time when skipping large unneeded sub-trees.
+
+It is also important to understand that the include/exclude rules are applied
+to every file and directory that the sender is recursing into. Thus, if you
+want a particular deep file to be included, you have to make sure that none of
+the directories that must be traversed on the way down to that file are
+excluded or else the file will never be discovered to be included. As an
+example, if the directory "`a/path`" was given as a transfer argument and you
+want to ensure that the file "`a/path/down/deep/wanted.txt`" is a part of the
+transfer, then the sender must not exclude the directories "`a/path`",
+"`a/path/down`", or "`a/path/down/deep`" as it makes it way scanning through
+the file tree.
+
+When you are working on the rules, it can be helpful to ask rsync to tell you
+what is being excluded/included and why. Specifying `--debug=FILTER` or (when
+pulling files) `-M--debug=FILTER` turns on level 1 of the FILTER debug
+information that will output a message any time that a file or directory is
+included or excluded and which rule it matched. Beginning in 3.2.4 it will
+also warn if a filter rule has trailing whitespace, since an exclude of "foo "
+(with a trailing space) will not exclude a file named "foo".
+
+Exclude and include rules can specify wildcard [PATTERN MATCHING RULES](#)
+(similar to shell wildcards) that allow you to match things like a file suffix
+or a portion of a filename.
+
+A rule can be limited to only affecting a directory by putting a trailing slash
+onto the filename.
+
+### SIMPLE INCLUDE/EXCLUDE EXAMPLE
+
+With the following file tree created on the sending side:
+
+> mkdir x/
+> touch x/file.txt
+> mkdir x/y/
+> touch x/y/file.txt
+> touch x/y/zzz.txt
+> mkdir x/z/
+> touch x/z/file.txt
+
+Then the following rsync command will transfer the file "`x/y/file.txt`" and
+the directories needed to hold it, resulting in the path "`/tmp/x/y/file.txt`"
+existing on the remote host:
+
+> rsync -ai -f'+ x/' -f'+ x/y/' -f'+ x/y/file.txt' -f'- *' x host:/tmp/
+
+Aside: this copy could also have been accomplished using the [`-R`](#opt)
+option (though the 2 commands behave differently if deletions are enabled):
+
+> rsync -aiR x/y/file.txt host:/tmp/
+
+The following command does not need an include of the "x" directory because it
+is not a part of the transfer (note the traililng slash). Running this command
+would copy just "`/tmp/x/file.txt`" because the "y" and "z" dirs get excluded:
+
+> rsync -ai -f'+ file.txt' -f'- *' x/ host:/tmp/x/
+
+This command would omit the zzz.txt file while copying "x" and everything else
+it contains:
+
+> rsync -ai -f'- zzz.txt' x host:/tmp/
+
+### FILTER RULES WHEN DELETING
+
+By default the include & exclude filter rules affect both the sender
+(as it creates its file list)
+and the receiver (as it creates its file lists for calculating deletions). If
+no delete option is in effect, the receiver skips creating the delete-related
+file lists. This two-sided default can be manually overridden so that you are
+only specifying sender rules or receiver rules, as described in the [FILTER
+RULES IN DEPTH](#) section.
+
+When deleting, an exclude protects a file from being removed on the receiving
+side while an include overrides that protection (putting the file at risk of
+deletion). The default is for a file to be at risk -- its safety depends on it
+matching a corresponding file from the sender.
+
+An example of the two-sided exclude effect can be illustrated by the copying of
+a C development directory between 2 systems. When doing a touch-up copy, you
+might want to skip copying the built executable and the `.o` files (sender
+hide) so that the receiving side can build their own and not lose any object
+files that are already correct (receiver protect). For instance:
+
+> rsync -ai --del -f'- *.o' -f'- cmd' src host:/dest/
+
+Note that using `-f'-p *.o'` is even better than `-f'- *.o'` if there is a
+chance that the directory structure may have changed. The "p" modifier is
+discussed in [FILTER RULE MODIFIERS](#).
+
+One final note, if your shell doesn't mind unexpanded wildcards, you could
+simplify the typing of the filter options by using an underscore in place of
+the space and leaving off the quotes. For instance, `-f -_*.o -f -_cmd` (and
+similar) could be used instead of the filter options above.
+
+### FILTER RULES IN DEPTH
+
+Rsync supports old-style include/exclude rules and new-style filter rules. The
+older rules are specified using [`--include`](#opt) and [`--exclude`](#opt) as
+well as the [`--include-from`](#opt) and [`--exclude-from`](#opt). These are
+limited in behavior but they don't require a "-" or "+" prefix. An old-style
+exclude rule is turned into a "`- name`" filter rule (with no modifiers) and an
+old-style include rule is turned into a "`+ name`" filter rule (with no
+modifiers).
+
+Rsync builds an ordered list of filter rules as specified on the command-line
+and/or read-in from files. New style filter rules have the following syntax: