def isStructure(s):
    """
    Checks if the structure constraint only contains "(", ")", and "." and legal fuzzy structure constraint characters.
    """
    returnvalue = 1
    for a in range(0, len(s)):
        if s[a] not in ".()[]{}<>":
            if s[a] not in "ABCDEFGHIJKLMNOPQRSTUVWXYZ":
                returnvalue = 0
    return returnvalue