def normalize_metric_name(name):
    """
    Makes the name conform to common naming conventions and limitations:

        * The result will start with a letter.
        * The result will only contain alphanumerics, underscores, and periods.
        * The result will be lowercase.
        * The result will not exceed 200 characters.
    """
    if not name[0].isalpha():
        name = 'x' + name
    name = name.lower()
    name = ''.join(['_' if not c.isalnum() and c != '_' and c != '.' else c for c in name])
    return name[:200]