import re


def isAsciiName(s):
    """
       Return true iff s is pure-ascii, and a syntactically valid XML name.

       >>> isAsciiName("a")
       True
       >>> isAsciiName("ab.-dc")
       True
       >>> isAsciiName("")
       False
       >>> isAsciiName(".foo")
       False
    """
    return re.match(r'^[A-Za-z\_\:][A-Za-z0-9\_\:\-\.]*$', s) != None