DOC: datetime: Updates based on Chuck's feedback

1 files changed, 16 insertions, 6 deletions

diff --git a/doc/source/reference/arrays.datetime.rst b/doc/source/reference/arrays.datetime.rst
index ae9ef1339..835f4431e 100644
--- a/doc/source/reference/arrays.datetime.rst
+++ b/doc/source/reference/arrays.datetime.rst
@@ -18,7 +18,11 @@ Basic Datetimes
 
 The most basic way to create datetimes is from strings in
 ISO 8601 date or datetime format. The unit for internal storage
-is automatically selected from the form of the string.
+is automatically selected from the form of the string, and can
+be either a "date unit" or a "time unit". The date units are years ('Y'),
+months ('M'), weeks ('W'), and days ('D'), while the time units are
+hours ('h'), minutes ('m'), seconds ('s'), milliseconds ('ms'), and
+more SI-prefix seconds-based units.
 
 .. admonition:: Example
 
@@ -164,14 +168,14 @@ a epoch of 1970-01-01T00:00Z. This means the supported dates are
 always a symmetric interval around 1970.
 
 ======== ================ ======================= ==========================
-      Time unit               Time span              Time span (years)
+      Date or Time unit         Time span              Time span (years)
 ------------------------- ----------------------- --------------------------
   Code       Meaning         Relative Time             Absolute Time
 ======== ================ ======================= ==========================
-   Y       year             +- 9.2e18 years         [9.2e18 BC, 9.2e18 AD]
-   M       month            +- 7.6e17 years         [7.6e17 BC, 7.6e17 AD]
-   W       week             +- 1.7e17 years         [1.7e17 BC, 1.7e17 AD]
-   D       day              +- 2.5e16 years         [2.5e16 BC, 2.5e16 AD]
+   Y       year (date)      +- 9.2e18 years         [9.2e18 BC, 9.2e18 AD]
+   M       month (date)     +- 7.6e17 years         [7.6e17 BC, 7.6e17 AD]
+   W       week (date)      +- 1.7e17 years         [1.7e17 BC, 1.7e17 AD]
+   D       day (date)       +- 2.5e16 years         [2.5e16 BC, 2.5e16 AD]
    h       hour             +- 1.0e15 years         [1.0e15 BC, 1.0e15 AD]
    m       minute           +- 1.7e13 years         [1.7e13 BC, 1.7e13 AD]
    s       second           +- 2.9e12 years         [ 2.9e9 BC,  2.9e9 AD]
@@ -216,9 +220,15 @@ The rules most typically used are 'forward' and 'backward'.
       File "<stdin>", line 1, in <module>
     ValueError: Non-business day date in busday_offset
 
+    >>> np.busday_offset('2011-06-25', 0, roll='forward')
+    numpy.datetime64('2011-06-27')
+
     >>> np.busday_offset('2011-06-25', 2, roll='forward')
     numpy.datetime64('2011-06-29')
 
+    >>> np.busday_offset('2011-06-25', 0, roll='backward')
+    numpy.datetime64('2011-06-24')
+
     >>> np.busday_offset('2011-06-25', 2, roll='backward')
     numpy.datetime64('2011-06-28')