void pattern

Empty element.

A data element is given by a gap.

Empty elements may occur everywhere in between other elements.

Some elements should not be expressed because they would virtually occur everywhere or because their expression would be confused with other content.

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.

• 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.

A gap can also be a sign of optionality where an element does not need to be expressed.

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.

• 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.

A void element is always derivation of some other data elements.