I&#x27;ve updated the NLTK issue tracker with information about how the model for NLTK&#x27;s built-in POS tagger was trained:
<a href="https:&#x2F;&#x2F;github.com&#x2F;nltk&#x2F;nltk&#x2F;issues&#x2F;1063#issuecomment-138005116" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;nltk&#x2F;nltk&#x2F;issues&#x2F;1063#issuecomment-138005...</a><p>The second edition of the book will include a &quot;scaling up&quot; section in most chapters, which shows how to transition from NLTK&#x27;s pure Python implementations to NLTK&#x27;s wrappers for the Stanford tools.