The B locus in dogs controls whether the dog is liver. Liver is recessive (b), so a dog needs two copies of the allele in order to be liver. If a dog is bb on the B locus then any and all black in its coat will become a brownish colour. Bb and BB have no effect.
Micro: Mini, small, tiny. Micro is also a term used in the RTS Starcraft, as a term for modified unit control. Micro can also refer to the descriptions of micro-organisms. Micro as a unit of measurement is defined as: One millionth..
The divisions are tracked by the prefix. In this case milli means [math]1/1,000[/math] of the original unit (divided by 10 three times). Similarly micro means [math]1/1,000,000[/math] of the original unit (divided by 10 six times). This said, for the milliamp [math]1 mA = 0.001 A[/math] and for the microamp [math]1 \mu A = 0.000001A[/math] then the milliamp is one thousandfold bigger than the microamp. For this reason there are 1000 microamps in a milliamp, or [math]1000\mu A = 1mA[/math].