How were dreams and visions seen in the context of Chinese Buddhism? This question is prompted by reading the 23rd Minor Precept in the Brahma Net Sutra


  After my passing, if a disciple should, with a wholesome mind, wish to
  receive the Bodhisattva precepts, he may make a vow to do so before
  the images of Buddhas and Bodhisattvas and practice repentance before
  these images for seven days. If he then experiences a vision, he has
  received the precepts. If he does not, he should continue doing so for
  fourteen days, twenty-one days, or even a whole year, seeking to
  witness an auspicious sign. After witnessing such a sign, he could, in
  front of images of Buddhas and Bodhisattvas, formally receive the
  precepts.


At the modern moment, the normal advice regarding dreams and visions is to ignore them. So while I appreciate the concern, I'm not mainly trying to get advice about what to do about dreams and visions.

What I see, in the above text is a positive perspective on dreams and visions, but the author assumes the reader knows what he's talking about when he says "vision"-- is this a reference to dreams, near-hallucinations during meditation, or "signs" like seeing something remarkable like crows listening to a dharma talk?  Is this a reference to dream yoga that I hear about in Vajrayana?
Good question. Most Buddhist teachers do advise us to try to ignore dreams and visions. Hard to do, sometimes. Still, in some places, they do place credence on dreams. During the Kalachakra Initiation, a 2 or 3-day affair, after the first day's teachings, the student is advised to try to remember his dream from that night.  [http://www.berzinarchives.com/web/x/nav/n.html_554862326.html] The common factor between your question and the above, perhaps, is that a Boddhisatva or a Buddha is presemed to be giving the initiation, and perhaps the dream, too. There is also a Dream Yoga practice in the "Six Yogas of Naropa" practices. [http://en.wikipedia.org/wiki/Dream_yoga]. In the advanced practice of the Completion Stage of the Mahamudra, the Six Yogas are practiced. One of them is the Dream Yoga practice, which is, again, only useful for advanced practioners. [http://www.berzinarchives.com/web/en/archives/advanced/mahamudra/karma_kagyu_mm/commentary_aspiration_prayer_definitive_meaning_mm/mm_prayer_commentary_02.html?query=six+yogas+of+naropa] Hope that helps.
ps. I tried to make a comment on your Brahma Net Project site, but for some reason the FaceBook login does not work on the network where I work. And I can not figure out how to get an account on your site. Maybe you need an "how to get an BNP site account for dummies page" there. Thanks.