3.10.13.11 The @scope attribute

• Set @scope to "local" when the resource is part of the current set of content.
• Set @scope to "peer" when the resource is part of the current set of content but might not accessible at build time, or for maps to be treated as root maps for the purpose of creating map-to-map key references (peer maps). An implementation might choose to open such resources in the same browser window to distinguish them from those with @scope set to "external".
• Set @scope to "external" when the resource is not part of the current information set and should open in a new browser window.
• See Using the -dita-use-conref-target value for more information on -dita-use-conref-target.

If no value is specified, but the attribute is specified on an ancestor within a map or within the related-links section, the value will cascade from the closest ancestor. The processing default is determined by the value of the @href attribute. In most cases, the processing default is "local". However the processing default is "external" whenever the absolute URI in the @href attribute begins with one of the following schemes:

• http
• https
• ftp
• mailto

Processors may consider additional URI schemes as "external" by default, but must not consider all absolute URIs as "external" by default. Processors MUST always consider relative URIs as "local" by default.