Madame Illa sells cement by the 50 kg bag, but she buys it from Ciments du Littoral by the tonne. Iron rods are sold by the bar and bought by the bundle of twenty. If Exowpee does not know how a tonne relates to a kilogram, or a bundle to a bar, stock and prices cannot be compared. Before she creates her products, Illa sets up the units she counts with. This page follows Illa as she defines them. The same steps apply to any business that buys in one format and sells in another, such as a drinks depot (bottle, crate) or a pharmacy (box, blister).

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Who works where

Measurement categories you create belong to your organization and are shared by all its companies. Built-in categories and units, such as the one Exowpee uses for bundles, cannot be changed. A separate list of the global kinds of measure, weight and volume, is used to give products a weight or a volume.

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Create a family of units

A family is a measurement category: weight, count, length. Illa starts with Create a measurement category. She names it “weight” and lists its units in the same step: the kilogram is the reference unit with a conversion factor of 1, and the tonne has a factor of 1000. Every other unit is expressed as a multiple of the reference unit. Later she needs one more unit, for the 25 kg sack of a new supplier. Add units to a category adds it. A new unit is always a multiple of the reference unit; it can never become the reference one.

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Read and correct

List measurement categories and View a measurement category show her families. List units of a category and View a unit of measure show the units. To know which global kinds of measure Exowpee uses for product weights and volumes, she uses List measurement types. A family is renamed with Edit a measurement category. A unit’s name or code is corrected with Edit a unit of measure. Its conversion factor cannot be changed, so a wrong factor means creating a new unit.

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Remove what is not used

Delete a unit of measure removes a custom unit, and Delete a measurement category removes a custom family with all its units. Both are refused while a unit of sale still uses them, a family also while a product uses it, and built-in ones cannot be removed. Units of measure are then used when you add units of sale to an item, as described in Set prices and units of sale.

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The rules

  • Built-in categories and units cannot be edited or deleted.
  • The name of a category is trimmed and lowercased, required, at most 120 characters, and unique among the organization’s categories. The name exowpee_bundle_count is reserved for the built-in bundle category: it cannot be used, and that category cannot be renamed or receive units.
  • Creating a category needs at least one unit. Exactly one unit is the reference unit, with a conversion factor of 1. Every other unit has a whole conversion factor greater than 1.
  • Unit names are stored lowercased and are unique within the category. Unit codes are at most 10 characters and unique across the organization, whatever their case.
  • A unit can only be edited for its name and code. The conversion factor and the reference flag cannot change.
  • The reference unit cannot be deleted while other units remain in its category.
  • A unit cannot be deleted while a unit of sale uses it. A category cannot be deleted while a product uses it or one of its units is used by a unit of sale.
  • Deleting is final: categories and units are not kept as deleted records. Deleting a category deletes its units.
  • The list of measurement types is the same for everyone. It needs no specific permission. Units appear in it only when you ask for them, ordered from the smallest to the largest conversion factor.

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