Add 'alternative term' for duration

[KaiSchnepf]

Description of the issue

This comes from PR #997 .
Which 'alternative terms' for duration should we add?

Ideas of solution

Some proposals:

• time duration
• temporal duration
• time span
• duration time

Workflow checklist

• I discussed the issue with someone else than me before working on a solution
• I already read the latest version of the workflow for this repository
• The goal of this ontology is clear to me

I am aware that

• every entry in the ontology should have a definition
• classes should arise from concepts rather than from words

[l-emele]

As already mentioned in the PR:

If there a doubts on the correct alternative term, then we should use the class name itself and that is duration.

Do we need really need an alternative term for duration?

[stap-m]

This comes from oeo-dev-mmeting no 30:

new concept: energy consumption value is an energy quantity value that measures the energy consumption over a (time/temporal) duration

The wording "...that measures the energy consumption over a duration" seemed incomplete, so the idea was to add an alternative term. #997

[l-emele]

In #997, there was this comment:

Is 'time duration' really an expression?

To me, this sounds also a bit awkward, however this expression seems to be used, see e.g. here.

Using time span as alternative term seems a bit tautological to me, as time-span is part of the current definition of duration: A duration is a quantity value indicating the time span of a one-dimensional temporal region, measured in a time unit.
But I have an a bit radical idea for a solution to that: Inverting the whole definition: A time span is a quantity value indicating the duration of a one-dimensional temporal region, measured in a time unit. Then time span would not be an alternative term, but the class name.
I was never really happy calling this class duration (but never commented on, as I am not such an expert on time-related concepts.

[stap-m]

Radical indeed, but no objections from my side.

[KaiSchnepf]

In #267 there was a very long discussion about that (I hoped it would be shorter, so I did not read everything).
Maybe you remember the arguments from other contributors, so we have more than two opinions because I do not know which terms are used in energy modelling.

[stap-m]

I scanned through #267, but I didn't find anything against @l-emele 's suggestion. Btw, we shouldn't put too much effort into this (rather minor) issue.