System IDs provide unique identification numbers for a Symphony project's content entries.
System IDs are unique, auto-incrementing, numerical values that are autogenerated for all content entries in a Symphony project. An entry’s system ID behaves like a hidden system field—invisible during entry creation and editing, but available to data sources for filtering, sorting, and output.
System IDs are auto-generated upon entry creation and are not editable.
The system ID field is available to data sources for filtering, sorting, and populating output parameters.
Whenever an entry is returned by a data source, its System ID is provided as an attribute in its XML.
<entry id="1">
<!-- Entry fields XML -->
</entry>Field types that create relationships among entries, such as Select Box Link, use system IDs to manage those associations. A section called "Children," for instance, might use a Select Box Link field called "Parent" to point to a section called "Parents." The field would store the parent's system ID, this way any of the parent entry's content could change and the link would still be maintained.