Using the MISSING= option to change the default missing numeric representation from a period to a space can cause the PUT statement to insert spaces between what should be consecutive delimiters when writing to a text file with the DSD option. See sample code and output below:

Sample program:

   options missing='';

   data _null_;
     file 'test.txt' dsd dlm=%str(';');
     x=.; y=2;
     put "SAS v&sysver";
     put '*' x :4. y :4. '*';
   run;

   options missing=.;

When run in SAS v9.1 the test.txt file contains the following:

   *;2;*

Nothing is output between the asterisk and the semi-colon, whereas in SAS v9.2 a single blank is written to the file for the missing numerical x:

   * ;2;*