If you choose to have heading numbers for all documents you have enabled the heading numbers on space level. You may not want numbers on page that have purely navigation purposes such as documents of type Space Index.

In this case use the space property suppress-heading-numbers-on-doctypes to switch off heading numbers for a selected set of document types. Per default

Not that this configuration can be overruled by enabling heading numbers on a particular document using enable-heading-numbers.

You may not need a heading number on a section for your documet. Like in the following example where the table of contents does not show the summary (and therefore does not number it).

Since the Summary section is not referenced in the table of contents (upper right side of the screenshot), the numbers differ. To align them, you either need to show the Summary section in the table of contents or suppress the heading number for the Summary.

Deselect the parameter Numbering in the macro editor for the Section Macro showing the Summary.

Now the heading numbers are aligned.

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In case you have a large document, like a specification or a architecture description using the arc42 Template, you may need more fine grained control of the numbering of a page.