You can't "allow to", you need "allow one to".
in SNMP replies, memory consumption values are usually specified in
KBytes and traffic flow on interfaces is specified in Bytes. Graphs
for these values will be more meaningful if values are represented in
-MBytes and mbps. The RRDtool graph command allows to define such
+MBytes and mbps. The RRDtool graph command allows one to define such
conversions. Apart from mathematical calculations, it is also possible
to perform logical operations such as greater than, less than, and
if/then/else. If a database contains more than one RRA archive, then a