The default principle of DIN EN ISO 8015 defines a procedure that minimises the number of entries in the specification. It is specified that, unless otherwise stated, a default defined in the standards is used. This can be a modifier, a parameter, unit or other specification. This means that „hidden“ rules must be known during interpretation. This can be critical for misinterpretations if not everyone involved in the product creation process is aware of the default.
The German standardisation committee also decided that the English term should not be translated and that „default“ should also be used in German.
The default for size dimensions, especially on cylinders, is explained as an example. The default is defined in DIN EN ISO 14405-1 as a two-point size dimension with the modifier LP. The modifier must not be entered if both tolerance limits are specified with this default. The following figure is therefore only a visualisation of the specification.
If you want to deviate from the standard state (default), this must be clearly labelled. This can be done using a modifier, such as the envelope condition, which is represented by an „E“ in a circle for size dimensions. The labelling can be done either directly on the respective dimension or as a general indication in or near the title block.
In the ISO GPS system, many defaults are defined in the relevant standards under the chapter „ISO default specification operator“ for the relevant specification.