anchor.diff:            pattern: '(0?[1-9]|(1|2)[0-9]|3[0-1])',
             maxlength: 2,
             required: true,
  +          title: 'Must be numeric eg 01',
             'aria-describedby': 'dob-hint'
           )
         %>
  
positive.code:           class: 'form-dob__input form-dob__input--year js-dob-year t-date-of-birth-year',
            pattern: '(19)[0-9]{2}',
            maxlength: 4,
            required: true
          )
        %>
  
negative.code:           class: 'form-dob__input js-dob-month t-date-of-birth-month',
            pattern: '(0?[1-9]|1[0-2])',
            maxlength: 2,
            title: 'Must be numeric eg 01',
            required: true
          )
        %>
  