Can you provide a small example of HOW you are using the reference data?   If the "reference" data is used to look up things, example product number to product name, price  or description then using that data to make a Format may be more flexible approach than actually combining data sets and manipulation.   @Danduke22 wrote: I have some  reference data that I've imported from a csv file. Then using a data step 1 - I've then stored them in arrays. I've then create a new data step 2 based around some transactions using macros but when I try to reference the arrays created in data step 1 it is not recognising them.   What is the best solution to overcome this scenario   Your help would be greatly appreciated!   ... View more