1. INTERLEAVING :
Interleaving combines individual sorted datasets into one sorted data set by specified variable in the By Statement
Before we interleave any SAS datasets they must be sorted by the same variable If the datasets are already indexed there is no need to sort them
ILLUSTRATION
SAS Code for Interleaving
DATA C;
SET A B;
BY ID value;
RUN;
Output:
The OUTPUT dataset C will be