wp-includes/link-template.php:2172Displays the relational link for the previous post adjacent to the current post.
$titlestringoptional'%title'$in_same_termbooloptionalfalse$excluded_termsint[]|stringoptional''$taxonomystringoptional'category'function prev_post_rel_link( $title = '%title', $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) { echo get_adjacent_post_rel_link( $title, $in_same_term, $excluded_terms, true, $taxonomy );}Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/link-template.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.