Sequence group formats

A Sequence group has either an Explicit or Implicit format.

Explicit
The explicit format relies on syntax to separate components. Each component can be identified by its position or by a delimiter in the data. Delimiters appear for missing components.
Implicit
The implicit format relies on the properties of the component types. The format is not fixed. If delimiters separate components, they do not appear for missing components.

For example, if each component of a fixed group has a fixed size, the component is distinguished from the next component by its position in the data. Or, a group may have delimiters that appear for missing components. In these cases, the format is apparent; the group has an explicit format.

If a group does not have an explicit format, it has an implicit format. An implicit format relies on the properties of the component types. In this example, the components make some pattern in the data and it is possible to distinguish between them, but the format is not fixed and if delimiters separate components, they do not appear for missing components.

When deciding what format a group has, it may help to ask first whether it is clear where one component ends and another begins. Generally, a group has an explicit format if the position of each component in the data stream is always the same or if a delimiter always marks the place for each component.


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