+dit(bf(--usermap=STRING, --groupmap=STRING)) These options allow you to
+specify users and groups that should be mapped to other values by the
+receiving side. The bf(STRING) is one or more bf(FROM):bf(TO) pairs of
+values separated by commas. Any matching bf(FROM) value from the sender is
+replaced with a bf(TO) value from the receiver. You may specify usernames
+or user IDs for the bf(FROM) and bf(TO) values, and the bf(FROM) value may
+also be a wild-card string, which will be matched against the sender's
+names (wild-cards do NOT match against ID numbers, though see below for
+why a '*' matches everything). You may instead specify a range of ID
+numbers via an inclusive range: LOW-HIGH. For example:
+
+verb( --usermap=0-99:nobody,wayne:admin,*:normal --groupmap=usr:1,1:usr)
+
+The first match in the list is the one that is used. You should specify
+all your user mappings using a single bf(--usermap) option, and/or all
+your group mappings using a single bf(--groupmap) option.
+
+Note that the sender's name for the 0 user and group are not transmitted
+to the receiver, so you should either match these values using a 0, or use
+the names in effect on the receiving side (typically "root"). All other
+bf(FROM) names match those in use on the sending side. All bf(TO) names
+match those in use on the receiving side.
+
+Any IDs that do not have a name on the sending side are treated as having an
+empty name for the purpose of matching. This allows them to be matched via
+a "*" or using an empty name. For instance:
+
+verb( --usermap=:nobody --groupmap=*:nobody)
+
+When the bf(--numeric-ids) option is used, the sender does not send any
+names, so all the IDs are treated as having an empty name. This means that
+you will need to specify numeric bf(FROM) values if you want to map these
+nameless IDs to different values.
+
+For the bf(--usermap) option to have any effect, the bf(-o) (bf(--owner))
+option must be used (or implied), and the receiver will need to be running
+as a super-user (see also the bf(--fake-super) option). For the bf(--groupmap)
+option to have any effect, the bf(-g) (bf(--groups)) option must be used
+(or implied), and the receiver will need to have permissions to set that
+group.
+
+dit(bf(--chown=USER:GROUP)) This option forces all files to be owned by USER
+with group GROUP. This is a simpler interface than using bf(--usermap) and
+bf(--groupmap) directly, but it is implemented using those options internally,
+so you cannot mix them. If either the USER or GROUP is empty, no mapping for
+the omitted user/group will occur. If GROUP is empty, the trailing colon may
+be omitted, but if USER is empty, a leading colon must be supplied.
+
+If you specify "--chown=foo:bar, this is exactly the same as specifying
+"--usermap=*:foo --groupmap=*:bar", only easier.
+