Changes

==Writing Metric==

==Writing Metric==

The rules of the SI system define not only the units but the ways in which they are to be written.

The rules of the SI system are defined in the [[International Standards Organization]] doucuments [[ISO 1000]] and [[ISO 31]]. They define not only the units, but the ways in which they are to be written.

* A space is to be put between the number and the unit. '25 km' is correct, '25km' is incorrect. This is a common mistake for users of English units, where no space is placed between the number and the unit.

* A space is to be put between the number and the unit. '25 km' is correct, '25km' is incorrect. This is a common mistake for users of English units, where no space is placed between the number and the unit.

* SI units do not take a trailing 's' to denote the plural. Thus '5 cms' is wrong and '5 cm' is correct. The reason is that 's' is the symbol for the second and 'cms' (intended to mean centimeters) could be confused with 'cm s' (meaning centimeter-seconds, a derived unit)

* SI units do not take a trailing 's' to denote the plural. Thus '5 cms' is wrong and '5 cm' is correct. The reason is that 's' is the symbol for the second and 'cms' (intended to mean centimeters) could be confused with 'cm s' (meaning centimeter-seconds, a derived unit)

* SI symbols do not take a trailing period. (This would be appropriate if they were abbreviations, but they are not.)

* SI symbols do not take a trailing period. (This would be appropriate if they were abbreviations, but they are not.)

* Since the SI symbols are symbols they are not altered to fit in with the surrounding text. The case of the symbol does not change - kelvin is always written as 'K' and kilograms is always written as 'kg'.  Furthermore, they are never written in italics. Thus <i>The woman lost 25 kg in weight</i> is incorrect and should be <i>The woman lost </i>25 kg<i> in weight</i>

* Since the SI symbols are symbols they are not altered to fit in with the surrounding text. The case of the symbol does not change - kelvin is always written as 'K' and kilograms is always written as 'kg'.  Furthermore, they are never written in italics. Thus <i>The woman lost 25 kg in weight</i> is incorrect and should be <i>The woman lost </i>25 kg<i> in weight</i>. Similarly, it is incorrect to alter the symbols to upper case (as often observed on shipping crates).

==Units of volume in the metric system==

==Units of volume in the metric system==