Prepackaging
Prepackages consist of product and packaging materials. The contents of prepackages must be measured in order to quantify the amount of product inside. That is where the legal metrology plays its role.

Terms
Some important terms that relate to prepackages are:
prepackage
package
prepackaged product
contents (of a prepackage)
quantity (of product in a prepackage)
net quantity
nominal quantity
actual quantity
maximum permissible error

Complete list
A large number of terms that relate to prepackaging originates in the European Council Directive 76/211/EEC (from 1976). Since that year terms are defined by OIML in R 79 and
R 87.

Both the OIML R 87 and the Council Directive are currently under revision. The scope might become broader when (besides weight and volume) length, width, area and count are included. Also the variable quantity is investigated.

Because of Dutch efforts in WELMEC Working Group 6 (on prepackages) a consistent set of definitions has been made that were suggested to OIML and the European Commission.

The definitions you will find here are the WELMEC definitions.

prepackage
A prepackage is defined as the combination of a product and the individual package in which it is prepackaged.

package
Individual package is everything that is meant to be left over after use, except for items naturally in the product. Use includes consumption or subjecting to a treatment.

Package is also referred to as packaging or packaging material(s).
Product is also referred to as commodity.

Explanation:
The two above definitions also defines the term ‘product’.

prepackaged product
A prepackaged product shall mean any single item for presentation as such to the ultimate consumer, consisting of a product and the packaging into which it was put before being offered for sale, whether such packaging encloses the product completely or only partially, but in any case in such a way that the contents cannot be altered without opening or changing the packaging.

contents (of a prepackage)
The contents of a prepackage is the quantity of product in a prepackage.

quantity (of product in a prepackage)
The quantity of product in a prepackage is the amount of product in a prepackage.

quantity (of product in a prepackage)
Product together with the package make up the prepackage and is by definition 'net' of package. Net quantity is therefore not defined.

nominal quantity (of product in a prepackage)
The nominal quantity of the product in the prepackage is the quantity indicated on the prepackage.
Note: The symbol Qn is used to designate 'nominal quantity'.

actual quantity (of product in a prepackage)
The actual quantity of the product in the prepackage is the quantity of product which the prepackage in fact contains.

maximum permissible error (of a prepackage)
The maximum permissible error in minus is the difference between the actual quantity and the nominal quantity of a product in the prepackage.

Explanation:
The symbol 'Fmax' is used to designate 'maximum permissible error in minus'.