ParameterLessons - Marine Metadata Wiki

Standard Naming Exercise

Parameter Lessons

This page contains lessons learned about the 'Parameter' element of our variable metadata.

One of the original notions was that a variable name could be made up of a domain, e.g., 'ocean', and a parameter -- what's measured there ('temperature').

We tried to make the parameter useful in the following context. If a person has the value of some entity, they'd like to know whether it can be compared to other entities. For example, voltages and currents can't be compared directly. So it's important to know if the value you have is a voltage, or is current.

What is Included in the ''Parameter''?

The parameter is the most basic term that can describe that variable. So wind direction, heading, and mooring orientation all just have a parameter of heading.

If two variables have the same parameter, they must be convertible to the same units.

If two variables have different parameters, they can not be compared, even though they may have the same units. For example, oxygen_dissolved and carbon_dioxide_dissolved may be in the same units, but can not be directly compared.

An interesting counterexample to consider is velocity, which was velocity when measuring the speed of something, but acoustic_velocity when referring to the speed of an entity (sound) in a medium (air). What makes acoustic_velocity different from all the other velocity measurements?

Which name to use for Parameter?

Although a few of us wanted to use rather abstract names for some of the parameters, we were overruled by the majority, who felt that a name commonly in science use was more appropriate. So although echo intensity and various backscatter measurements all measuring the intensity return of a signal, the group preferred to call the first echo_intensity and the second optical_backscatter (rather than, for example, intensity_acoustic_return and intensity_optical_return).

To apply this "use the common term" more thoroughly, we should probably change oxygen_dissolved and carbon_dioxide_dissolved to put the word 'dissolved' first.

What order should Parameter terms be specified?

• Putting most general concept first makes it easy to search and find in sorted lists

• • oxygen_dissolved, oxygen_saturated

  • velocity, velocity_acoustic

• Putting most specific concept first makes it more human-recognizable

• • optical_backscatter

  • acoustic_velocity

• We ended up choosing human-recognizable terms

• • Possibly we should also have synonyms which are more systematic

Formatting

How should words be separated -- spaces, underlines, or mixed case (capital letters beginning each word after the first)? Are there any technical reasons to choose one format over another? It should be possible to go back and forth pretty easily.

Spaces are discouraged, because they introduce too many potential incompatibilities.

As the typist I tended to choose underlines for no particular reason, but wasn't 100% consistent.

Definitions

• qcflag: a value which describes the quality of another (single) value

• quality_statistic: a number which describes a set of values as a whole