Cheshire Cat Computing

I've got confused whether I should update rrd database with data in bytes or in bits.Is it right that if I use the option Options[_]: bits then I should use data of bits to update the rrd database?
But what's contrary to this is something I found in the file mrtg\contrib\cisco_BPX_MGX\howto.html:
Target[Switchname_2.1]:.1.3.6.1.4.1.351.100.4.2.4.4.1.25.X0YZ000&.1.3.6.1.4.1.351.100.4.2.4.4.1.26.X0YZ000:community@x.x.x.x*53
#multiply above by 53(53 bytes in a cell)

Options[Switchname_2.1]:bits
bits :All the monitored variable values are multiplied by 8,is it done by MRTG itself or need I to add *8 at the end of the target?
It has used the option of bits,then why the target is in bytes? Will you please tell me is it right and when to update in bytes and in bits.Thanks