[uf-new] Measurement brainstorming

Guillaume Lebleu gl at brixlogic.com
Fri Sep 28 09:10:05 PDT 2007

```There has been already a lot of work in researching measurement
examples, existing practices and brainstorming.
http://microformats.org/wiki/measure-brainstorming

One of the main issue that I remember we could not agree on was how to
deal with composite measure units.

The simplest approach is to mark up composite measure units as if they
were elementary units. For instance a gram is really a composite unit
(1/1000 * 1 kg), but we would nonetheless mark up "500 g" as "500<abbr
class="unit" title="gram">g</abbr>" for simplicity purpose. The problem
is the large amount of units that would result from this (see UNECE list
http://www.unece.org/etrades/units.htm) and the difficulty of a program
to do conversion.

The other approach is the one used by XBRL
(http://microformats.org/wiki/currency-formats#XBRL) where composite
units are explicitly marked up as composite. This has the advantage of
making comparison and conversions much easier (Of course, in the example
above (500 g), this approach would not work since "1000" does not appear
in the human-readable part of the content). But forcing every single
composite unit to be marked up explicitly would be too complex for broad

One way I see that may allow to resolve this conflict would be to follow
the XBRL approach and have both a microformat for:

* defining elementary/atomic units. ex. "kg is the SI unit of mass".
* defining composite units as composition of other units and scaling
factors, for instance to mark up "One gram (g) is 1/1000th of a kg".
* referring to these definitions when marking up content such as
"500 g".

The most used elementary and composite definitions could be anywhere
(ideally on the Web pages of the organizations who define them), but I
think it may be useful to put the most used ones on the microformat wiki.

Guillaume
```