alias ~ Empty element.
idea ~ A data element is given by a gap.
context ~ Empty elements may occur everywhere in between other elements.
motivation ~ Some elements should not be expressed because they would virtually occur everywhere or because their expression would be confused with other content.
implementations ~ An embedding or schema can indicate the context in which data can be read from gaps. The separator pattern is typically applied in form of borders around the gap.
examples
~ - An empty string is not given as such but by an empty
embedding (""). The same applies to other empty instances
of sequence and container.
- Default values are not given explicitly. Even if no default
values are defined, one could just omit an element to indicate
another value: a missing value is also a value.
- Unit types in data type systems are not visible as data but by
referencing them in other structures.
- Assumed rules can lead to implicit derivation of data that
is not directly expressed (for instance affiliation to
superclasses and derived RDF statements).
- Given a comparison rule for equality of elements, one
automatically gets an unexpressed normalized form of each
element.
counter examples ~ A gap can also be a sign of optionality where an element does not need to be expressed.
difficulties ~ As empty elements may occur virtually everywhere between other elements, it is difficult to spot empty elements and irrelevant empty elements may wrongly be assumed.
related patterns ~ - Optionality is an alternative to the void pattern. - If elements are cropped to a maximum length or form the original, full form is implicitly given (etcetera). - The garbage pattern is kind of the contrary to the void pattern: void is content without form, garbage is form without content.
implied patterns ~ A void element is always derivation of some other data elements.