Data Transformation Engine Type Designer Reference Guide

Chapter 13 - Distinguishable Objects A Group’s Starting Set
A Group’s Starting Set
Data objects in a data stream need to be distinguishable when they could belong
to two different groups. Specifically, the difference between the data that can
come first in one group and the data that can come first in the other group. All of
the possible types of data that may appear first in a group are referred to as the
group’s starting set.
The following describes the starting set of a group based on its group format:
Group Format Starting Component Set
Explicit
Delimited Includes the type of its first component.
Fixed Includes the type of its first component.
Implicit
Sequence Includes the type of all components up to and including
the first component that has a minimum range of at
least one.
Unordered Includes the type of each component.
Choice Includes the type of each component.
For example, suppose File Root is an implicit sequence group with the following
components:
The starting set of File ROOT includes all the types that may appear first in a File
ROOT group. A File ROOT could begin with a Statistics Record. If there is no
Statistics Record, the File ROOT could begin with a Comment Record. If there
is no Statistic Record and no Comment Record, the File ROOT could begin
with a CustomerID Record. However, the File Root could never begin with a
Transaction Record because CustomerID Record with a default component