@cancan101 @jreback Just to make sure I understand, these accessors need to be frequency aware for the freq of the Timestamp/DatetimeIndex. e.g.

```python
x = pd.Timestamp('2013-06-30', offset='Q-JUN')
x.is_end_year
1

x = pd.Timestamp('2013-06-28', offset='BQ-JUN')
x.is_end_year #29th, 30th are not business days
1 
```

Annual and quarterly frequencies define the year end month.  Weekday freqs force beginning/end of periods to be on weekdays. Should I add is_beg/end_week accessors for weekly freqs? Do I need to worry about custom business days? Anything I am not covering?