to access all RRD functions as of RRDtool 1.0.13. All command names
and arguments are equal to those of RRDtool. They are assigned to the
namespace `Rrd', e.g. `Rrd::create'. Return values are a bit
-different from plain rrdtool behavior to enable more native Tcl
+different from plain RRDtool behavior to enable more native Tcl
usage. Errors are mapped to the TCL_ERROR return code together with
the RRD error strings.