-Start I/O at the provided offset in the file, given as either a fixed size or a
-percentage. If a percentage is given, the next \fBblockalign\fR-ed offset will
-be used. Data before the given offset will not be touched. This effectively
-caps the file size at (real_size - offset). Can be combined with \fBsize\fR to
-constrain the start and end range of the I/O workload.
+Start I/O at the provided offset in the file, given as either a fixed size in
+bytes or a percentage. If a percentage is given, the next \fBblockalign\fR-ed
+offset will be used. Data before the given offset will not be touched. This
+effectively caps the file size at (real_size - offset). Can be combined with
+\fBsize\fR to constrain the start and end range of the I/O workload. A percentage
+can be specified by a number between 1 and 100 followed by '%', for example,
+offset=20% to specify 20%.