[Tutor] Regex confusion

[Jeffrey N. Shelton]

Hi!

I'm looking at some Python code (from the DT_HTML.py module of Zope,
actually) that uses a regex expression that I can't figure out. Perhaps you
could point me in the right direction?

     name_match=regex.compile('[\0- ]*[a-zA-Z]+[\0- ]*').match
     end_match=regex.compile('[\0- ]*\(/\|end\)',regex.casefold).match
     start_search=regex.compile('[<&]').search

The phrase "[\0- ]" in the first two lines confuses me. Is this a group
reference? And if so, what is group 0? I thought the numbering for match
groups started at 1. Logically, it would seem that it this phrase is a means
for grabbing up leading and trailing dashes and whitespace. But it's beyond
me to figure out how "\0" figures into this.

Also, the ampersand (&) in the third line is a problem for me. I've looked
through my copy of "Mastering Regular Expressions" and can't find any
reference to a "&" metacharacter. What am I overlooking?

Thanks for the help!

Jeff