alias ~ Delimiter.
idea ~ An element indicates the boundary between two other elements.
context ~ A sequence with at least two elements and a third separator element.
motivation ~ Indicate borders and connections between data elements.
implementations ~ Select data elements that must not occur in normal content (prohibition) or mark an element as (non)separator by a flag. A schema can tell which separators to use at which places.
examples
~ - Whitespace characters separate words.
- Brackets and delimiters, such as {, [, (, ), ], }
and ,, |, ;, : etc. are used as separators in JSON, INI,
CSV and other data structuring languages. Similar characters are
also popular for ad-hoc structuring of values, for instance to
create lists and annotations.
- ASCII defines four level separator characters (code 28 to 31).
- Lines in conceptual diagrams are used as borders and
connections.
counter examples ~ Being a separator is not an inherent property of a data element, so whitespace, brackets and delimiters may also occur as normal content.
difficulties
~ - Parts of elements can be misread as separator and vice versa.
- Most elements divided by separators are divided by separators on
their parts. Such hierarchic embeddings can be read ambiguously
(for instance "( { ) }").
- It is not obvious whether separators indicate borders and
connections between elements on the same level (for instance
arrows in a diagram) or whether they also combine elements by
subsumption (for instance subfield indicators).
- In sequences it must be clear whether separators occur between,
after, or before an element, otherwise one can unintentionally
introduce empty elements, for instance by ending a
comma-separated list with a comma.
related patterns ~ - One can alternatively use data elements of known size so no explicit delimiters are needed. - Separators can simultaneously act as flag to indicate the type of a connection. - If the actual form of a separator does not matter, the separator element is an example of the garbage pattern.
implied patterns ~ An embedding gives context to separating elements and makes clear which data elements are actually separated and connected.