Define a unified way of writing prices, unit prices and weights, volumes etc.

[drummer83]

This issue is about a standardized spelling of prices, unit prices, weights etc. Currently there are different ways mixed up in our software and they don't always comply with standards (see screenshots).

According to the International System of Units (SI-System) it is a standard to write amounts and units in the following way:

Weight, volume etc.:

• 3.5 kg (with a blank space before the unit)

Division (Unit price):

• 3.95 €/kg (with a blank space before the unit and no blank spaces before and after the "/")
• £3.95/kg (no spaces after the currency and no blank spaces before and after the "/")

Prices:

• 3.95 € (with a blank space before the unit)
• £3.95 (no blank space after the unit)

There are some open discussions about topics around this, like wishlist issue openfoodfoundation/openfoodnetwork#9160 and unit prices (which also takes into account the reading by screen reading software).

It would be great to have a general proposal by a designer how to do it in a formally correct and unified way that is commonly used and accepted by users.

After that we should have the proposal confirmed in a Product Circle meeting and implement it in our software.