1. ISO 8601 and SAS ®: A Practical Approach
Derek Morgan
PAREXEL International

2. Section 1: What Is ISO 8601?

3. The ISO 8601 Standard
Internationally accepted methodology describing dates and times using numbers
Standard covers:
Dates
Time of day
Date and time
Coordinated Universal Time (UTC)
Local time with offset to UTC
Time intervals and recurring time intervals

4. The ISO 8601 Standard Removes problems of: Translation
August can be expressed as “août”; “август”; “agosto”; “八月”
Local norms for expressing dates
Is it March 8, 2016 or August 3, 2016?

5. Basic vs. Extended Notation
Basic is just the numbers
Extended uses delimiters
Basic Notation
Extended Notation
2016
201606
T1422
T14:22
T142237
T14:22:37 T
T14:22:37.74

6. Section 2: SAS ® and ISO 8601

7. A Few Basics
SAS maintains dates and times as numbers relative to a reference point
Needs an exact number
ISO 8601 allows for missing components
In standard SAS dates and times, missing components=missing value
SAS can handle ISO dates with missing components
Separate from normal SAS dates and times if you need it

8. Reading Extended Notation ISO 8601 Dates and Times into SAS ®
Use informats - No different than any other complete SAS date, time or datetime
Create a SAS datetime from an ISO 8601 datetime:
xxxdtm = INPUT(xxDTC,E8601DT.);
Create a SAS date from an ISO 8601 date (or datetime):
xxxdt = INPUT(xxDTC,E8601DA.);
BUT pick the time from the complete SAS datetime created above
xxxtm = TIMEPART(xxxdtm);

9. Reading Basic Notation ISO 8601 Dates and Times into SAS ®
The informats for basic notation begin with the letter “B”
Create a SAS datetime with B8601DT.
Create a SAS date with B8601DA.
STILL pick the time from the complete SAS datetime you created using TIMEPART()
WARNING!!!
Basic notation informats will substitute 0 for missing time components, and 1 for missing day or month components!

10. Basic vs. Extended Notation Informats
ISO 8601
Character String
Read with E8601DT.
Read with B8601DT.
T16:14
26MAR2014:16:14:00
24JUN2014:00:00:00
01SEP2014:00:00:00
You may wind up with an unexpected imputation using the basic notation informat!

11. Writing ISO 8601 Dates and Times in SAS ® the Normal Way
Use formats - No different than any other complete SAS date, time or datetime.
IF dt_value is a valid SAS datetime value:
vsdtc = PUT(dt_value,E8601DT.) creates an ISO 8601 datetime
vsdt = PUT(dt_value,E8601DN.) creates an ISO 8601 date from a datetime
vstm = PUT(TIMEPART(dt_value),E8601TM.)

12. Writing ISO 8601 Dates and Times in SAS ® the Normal Way
IF dt_value is a valid SAS date:
vsdt = PUT(dt_value,E8601DA.) creates an ISO 8601 date

13. SAS ® ISO 8601 Facility Stored internally in CHARACTER variables
Needs CHARACTER formats and informats to make any sense, just like normal dates and times
Can accommodate missing components
Can perform simple, automatic imputation in calculations
This may not be what you want
Recommend doing any imputation before using this for calculations

14. How SAS ® Stores ISO 8601 Values
Original ISO String
SAS Datetime Value
Formatted SAS Datetime Value
SAS ISO  Internal Value
T15:05:30
20APR2015:15:05:30
FFD
T06:40
22DEC2016:06:40:00
2016C220640FFFFD
FFFFFFFFD
20159FFFFFFFFFFD
T02
FFFFFFD
2016
2016FFFFFFFFFFFD

15. ISO 8601 Durations and Intervals
Duration describes a period of time:
PT17H41M
P2DT10H30M
Intervals describe start and end of a period
3 Forms:
Datetime/Datetime: T17:19/ T11:00
Datetime/Duration: T17:19/P0Y0M0DT17H41M0S
Duration/Datetime: P0Y0M0DT17H41M0S/ T11:00

16. How Do You Calculate ISO Durations and Intervals?
Divide end date-start date by several factors to get years, months, days, hours, etc.
- or -
Use the SAS interval function INTCK() to get years, months, days, hours, etc.
Concatenate the results with the appropriate delimiters

17. There’s An Easier Way
DATA duration1; SET full_datetimes; LENGTH aedur $ 32; CALL IS8601_CONVERT('dt/dt','du', aestdtm,aeendtm,aedur); FORMAT aedur $N8601E.; RUN;
Event Start Date/Time
Event End Date/Time
Duration
22DEC2016:00:00:00
23DEC2016:00:00:00
P1D
15JAN2014:00:00:00
04JUN2014:00:00:00
P4M20D
25FEB2013:00:00:00
16MAY2017:00:00:00
P4Y2M19D

18. The IS8601_CONVERT Routine
Syntax:
CALL IS8601_CONVERT(convert-from, convert-to, <from-variables>, <to-variables>, <date-time-replacements>);
Works with SAS ISO datetimes and SAS datetimes, interchangeably.

19. And That’s the Practical of it...
The ISO 8601 standard is an internationally accepted methodology describing dates and times using numbers
There are informats to read ISO 8601 dates and times
There are formats to write ISO 8601 dates and times
SAS can handle missing components in ISO 8601 dates and times - separate facility from normal dates and times
The IS8601_CONVERT routine calculates ISO durations easily

20. Any Questions? References:
Harnessing the Power of SAS® ISO 8601 Informats, Formats, and the CALL IS8601_CONVERT Routine; Kim Wilson, SAS Institute Inc., Cary, NC, USA, PharmaSUG 2012
The Essential Guide to SAS® Dates and Times, Second Edition. Cary, NC: SAS Institute Inc.; Morgan, Derek P
And that's it.

21. Derek Morgan, PAREXEL International
Thank You!
Derek Morgan, PAREXEL International