add value "kg/kg" to "unitType" enumaration

[hurni]

To indicate usage of plant protection products, certain business partners use percentage and others indicate the absolute mass of two products as befitting their needs. Although percentage can be calculated, relevant information is lost that can be used in other use cases (e.g. if an absolut maximum of a product is allowed on an acreage, etc.)
medium/long term the business partners may be persuaded to harmonize. But in the meanwhile, digiflux needs to be able to use "kg/kg" as an additional unitType.

cp. blw-ofag-ufag/eCH-0263#59

[hurni]

@RyanStuder-Work: kannst du bitte kurz die Erklärung und den Lösungsvorschlag gegenprüfen? Danke

[AFoletti]

Confirmed minor and planned for V1.5

[hurni]

included in Branch Release-1.5.0: https://github.com/blw-ofag-ufag/eCH-0261/edit/Release-1.5.0/src/eCH-0261-1-0.xsd

[montanajava]

The question in my mind is one of redundancy. We already have %, as is well known.

% is a dimensionless unit that expresses a ratio as a fraction of 100. kg/kg is also dimensionless because it expresses a ratio where the units cancel out. A ratio of 0.5 kg/kg means 50%

Clearly, a specific user group will benefit in terms of context and clarity by adding a specific notation.

However, the eCH standard for Agricultural data has heretofore been steadfast in resisting multiple ways of expressing specific unit categories such as weight or volume. The working groups have also consistently communicated that a specific system can use any unit of measure it wishes internally but use the standard for interfaces.

[AFoletti]

Thanks @montanajava for your input. @hurni and myself we would like to point out the following:

• the change will go through the AG-review and can always be removed
• you are right when you say that this is somewhat redundant with "%", but this only carries a part of the information. If the source system tracks a mix per weight, I need to know that because the same mix can have a completely different % value if tracked per volume. The system is far from perfect and we do not like this Kg/Kg very much, but we see it's potential in the standard how it is right now, where it is not possible to better inform a % measurement