Non-si Unit Prefix

Some of these were never part of any actual system of measurement. A few were proposals that were rejected. None are in common use, and many of the powers of ten they represent are already taken by SI prefixes.

One such prefix is ''bronto'', used in the fake term ''brontobyte''. References on the World Wide Web suggest meanings of the bronto prefix to be variously any of 10¹⁵, 10²¹, 10²⁴, or 10²⁷. SI has already produced standard prefixes for 10¹⁵ ( Peta ), 10²¹ ( Zetta ) and 10²⁴ ( Yotta ).

The prefix ''guaca'' is a Chemistry joke arising from these facts:

Guacamole is made of Avocado , which sounds (with apologies to the learned professor) remarkably like Avogadro .

Guacamole is spelled (if not pronounced) remarkably like Yocto mole.

A mole is made of Avogadro's Number of molecules.

A single molecule is made of about 1.66 yoctomoles.

A yoctomole is about six tenths (0.602) of a molecule.

A guacamole must be one molecule, much more convenient.

From this it follows that ''guaca'' must be $1/N_A = 1.660539 imes 10^{-24}$ .

There are many other unofficial prefixes. Some of them appear to come from a numerical Greek root indicating the power of 1000 the prefix means. These prefixes are as follows:

OBSOLETE PREFIXES

There are some prefixes that were used in some older versions of the Metric System but that are not part of SI . The prefixes 'myria' and 'myrio' came from the Greek μύριοι (mýrioi), meaning both ''ten thousand'' and "an indefinite large number". There is no Latin equivalent. Adopted by the French in 1795 , they were not retained when the SI Prefix es were agreed internationally by the 11th CGPM in 1960 .

They are still sometimes used as a prefix for constructing words:

Myriad = 10,000 of anything (often used figuratively to mean "a great many" in English )

Myriagon = a 10,000 sided polygon.

Myriapoda = a group of creatures including the Centipede s and Millipede s.

Also obsolete are metric double prefixes, such as those formerly used in micromicrofarads, hectokilometres, micromillimetres, and so on.

PROPOSED SYSTEMS

A proposal of Jim Blowers can be found [http://jimvb.home.mindspring.com/unitsystem.htm here]. This describes the naming scheme as follows:

zetta is z + -etta, which is an alteration of septi-, meaning 7, as 21 is 7 groups of three. yotta is y + -otta, an alteration of octo-, meaning 8. The pattern here is that we go backwards from the beginning of the alphabet, starting with z and y, and we follow it up with an alteration of the Greek or Latin for the next number. According to this pattern, the next ending should be xona-, since x comes before y in the alphabet, and 9 is noni- in Latin. Similarly, 10³⁰ should be weka-, since w precedes x and 10 is deka in Greek.

There have also been proposals to use the units of one of these systems with prefixes of a different base than ten, e.g. Binary , Duodecimal or hexadecimal.

EXTERNAL LINKS

Proposal to extend system of units from 10⁻⁶³ to 10⁶³

[http://news.bbc.co.uk/1/hi/magazine/3673262.stm BBC article suggesting that a brontobyte is 10²⁷ bytes]

[http://www.sybase.com/content/1031253/EnterpriseUnwired.pdf Sybase article suggesting that a brontobyte is 10²⁴ or 10²⁷ bytes] (Note article's table a few pages down. Note also it mistakenly places 1 terabyte = 1,000 megabytes. It should be 1 terabyte = 1,000 gigabytes. Also yottabyte is shown incorrectly as zottabyte. With those corrections, it also is clearly 10²⁷.)

[http://www.ucl.ac.uk/~uczcw11/modules/p028l03.ppt Article suggesting that a brontobyte is 10²¹ bytes]

[http://openc.k12.or.us/sitedocs/styleguide/abbreviations.html Article suggesting that a brontobyte was 10¹⁵ bytes before the creation of the prefix peta-] (Article is of dubious authority... suggests that Greek letters ν, π, and φ are SI prefixes for nano-, pico-, and femto-, instead of n, p, and f.)

[http://www.pcsndreams.com/Pages/Articles/Megabytes.htm Article suggesting that brontobyte is 10²⁷ bytes]

Moerner Lab Single-Molecule Research Page (Jokingly defines 1 guacamole = 1 / (''Avocado's'' number) of moles. First archived in 2001 but the definition was up c.1996)

Jargon file entry for "quantifiers" Claims that groucho, harpo, grouchi, and harpi have gained the general approval of Usenet.

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Non-si Unit Prefix