Change the ID Prefix and Separator

When an AsciiDoc processor auto-generates section IDs, it begins the value with an underscore and uses a hyphen between each word. These characters can be customized with the idprefix and idseparator attributes.

Change the ID prefix

By default, the AsciiDoc processor begins an auto-generated section ID with an underscore (_). You can change this prefix by setting the idprefix attribute and assigning it a new value. The value of idprefix must begin with a valid ID start character and can have any number of additional valid ID characters.

:idprefix: id_

If you want to remove the prefix, set the attribute to an empty value.

:idprefix:
If you set the idprefix to empty, you could end up generating IDs that are invalid in DocBook output (e.g., an ID that begins with a number) or that match a built-in ID in the HTML output (e.g., header). In this case, we recommend either using a non-empty value of idprefix or assigning explicit IDs to your sections.

Change the ID word separator

The default section ID word separator is an underscore (_). You can change the separator with the idseparator attribute. Unless empty, the value of the idseparator must be exactly one valid ID character.

:idseparator: -

If you don’t want to use a separator, set the attribute to an empty value.

:idseparator:
When a document is rendered on GitHub, the idprefix is set to an empty value and the idseparator is set to -. These settings are used to ensure that the IDs generated by GitHub match the IDs generated by Asciidoctor.