> 4) Does pyyaml currently insist on a blank after a colon for a good reason? Would eliminating the requirement introduce an ambiguity?
>> I'm still interested in answers to questions 1, 2, and 4 above.  And if someone has something further to add to #3, I certainly wouldn't be displeased ^)^

My understanding is that the answer to 4. is, e.g.,

- http://www.google.com
- http://www.amazon.com

If you didn't insist on a blank after the colon, there would be
extra hashes/mappings in there.