The link/button text more specifically, are those which starts with (non case sesitive) "Next", "Prev", "Previous";
or ends with "Prev", "Back", "Previous", "Next". e.g. "Next", "> Next", "Next Page", "Prev", "< Prev", "< Previous", etc.
but not "< Prev Page" because the word "prev" or "previous" is not at the start/end of text.
The ID and class names are also checked.
This script doesn't take into account of links whose contents is an image rather than text, or whose text is a CSS text contents.
If next/previous navigation link is specified in the HTML metadata, it will be used as a priority.