ID variables ;

The ID statement identifies the variable(s) from the DATA= data set to be included in the OUT= data set. When this statement is omitted, PROC HAPLOTYPE creates in the OUT= data set the variable _ID_ that contains a unique numeric identifier for each individual. When the TALL option is used, this statement is ignored, and the INDIVIDUAL variable is automatically included in the OUT= data set along with the trait variable if the TRAIT statement is specified.