6.2 HOW TO USE SI UNITS
1. Beware upper/lower case letter in many cases they can change meanings.
2. Try to move prefixes out of the denominator of the units.
4. Use a dot in compound units.
5. Use spaces to divide digits when there are more than 5 figures, commas are avoided because their use is equivalent to decimal points in some cultures.
In some cases units are non-standard. There are two major variations US units are marked with `US' and Imperial units are marked with `IMP'.