I don't see a clear way to do this. The problem is that these are not actually ISO8601 values, at least according to SAS.

SAS recognizes two versions of ISO: Basic (B8601DZ.) and Extended (E8601DZ.). Basic has no colons/dashes/etc., and Extended has all possible ones.

• Basic: 20130119T094039812+0000
• Extended: 2013-01-19T09:40:39.812+00:00

(see the doc page on ISO date/times for more information)

Yours are an amalgamation of the two, and SAS doesn't seem to like that.

Add to that the fact that you're reading this from a delimited file, and I don't see a good single pass solution. I think your method is fine. You can probably skip the substring, but otherwise you will be stuck.

Your input above doesn't work because you can't use informats in a list input method like that; if you prepend a : then the informat will be used, but unfortunately you can't actually use it to limit the incoming text to the informat (not sure why - it can in other contexts). IE:

input a :e8601dz19. b :e8601dz19. c :$4.;

That's legal, but doesn't help you, as it tries to stick the 28 long bit into that (I'm not sure if it's right-aligning it perhaps, but it's definitely not left-aligning it like it would in formatted input). You're using formatted input but mean to use modified list input, hence the issue.

You could do this, if you didn't have all that missing data, for example:

data _null_;
infile datalines dlm=',' dsd missover;
informat a b e8601dt19.;
input 
@1 a e8601dt19. 
@"," b e8601dt19.
@"," c $4.;
format a b is8601dt.;
put a= b= c=;
datalines;
2013-01-19T09:40:39.812+0000,2013-01-19T09:40:39.812+0000,text
,2013-01-19T09:40:39.812+0000,text
 , ,text
;
run;

That works for the first line, basically reading the first 19 into a and then skipping to the next comma and reading the b. But notice it fails for every other row, because it eats up too many characters for a. Anything you do to adapt this to work (which probably could be done) is going to be far more than you'd do just substringing.

I would do this:

data _null_;
infile datalines dlm=',' dsd missover;
informat a b e8601dt19.;
length a_c b_c $28;
input 
a_c $ b_c $ c $;
a = input(a_c,??e8601dt19. -l);
b = input(b_c,??e8601dt19. -l);
format a b is8601dt.;
put a= b= c=;
datalines;
2013-01-19T09:40:39.812+0000,2013-01-19T09:40:39.812+0000,text
,2013-01-19T09:40:39.812+0000,text
 , ,text
;
run;

No substring necessary, just use the w to shorten to 19. Or add the : programmatically if you would like the TZ information used.