What is the ac:local-id parameter from a macro used for?

[S Laureano]

I've seen this parameter in Confluence Cloud macros and I'd like to know

• What is that parameter used for? Is it that important? 
• Does this parameter only appears in Confluence Cloud macros? (this is because I'd like to difference between Confluence cloud and DC macros)

[Thiago P _Atlassian Support_]

Hey there @S Laureano ,

The 'ac:local-id' parameter serves as a unique identifier for certain elements such as macros, tables, images, captions, and other content blocks within a Confluence page's Storage Format. It also used to correlate elements from Storage Format to their corresponding nodes in IDF and is used during migrations.

It is most widely used in Confluence Cloud as DC uses a similar 'ac:macro-id' instead.

Hope this helps! =]