The v30 release introduced new relative options for article and page navigation. Note that relative navto formats are supported only in v30 or later apps, but you can use any folio format (v20 or later). Relative navto links are supported in the iOS and Windows Store viewers, but not yet supported in the native Android viewer or web viewer.
You can use various navto://relative formats to jump to the next, previous, first, or last article. For example, a button with a navto://relative/first action jumps to the first article in the folio. Valid formats include first, last, next, previous, and current. You can also jump to a specific article relative to its position in the folio, such as the fifth article.
Example: navto://relative/last (jumps to last article in folio)
Example: navto://relative/last#last (jumps to last page of last article in folio)
Example: navto://relative/4 (jumps to fifth article in folio)
Example: navto://relative/4#2 (jumps to third page of fifth article in folio)
Using the "current" format is especially useful for page navigation. You can use #previous, #next, #first, #last, and you can jump to a specific page, such as #3 to jump to page 4 of the article.
Example: navto://relative/current#previous (jump to previous page in article)
Example: navto://relative/current#last (jumps to last page in article)
Example: navto://relative/current#3 (jumps to fourth page in current article)
In Smooth Scrolling articles, you can use decimals or percentages to jump to a specific position.
Example: navto://myarticle#3.3 (jumps to a specific position in smooth scrolling article that displays the bottom of page 4 and the top of page 5)
Example: navto://myarticle#50% (jumps to the middle of smooth scrolling article)
To extend these relative navto capabilities, you can create a Web Content overlay or HTML article that accesses the Reading API. For example, you can query the folio to determine information such as how many articles are in the folio and how many pages are in an article. You can then display this information or use it in another way within the overlay or HTML article. For more information, see New APIs and features in r30 in DPS Developer Center.