I had to google SAS EAS - is that SAS Education Analytic Suite? It looks like that just means its good old SAS licensed to a College or University. Also, when you say "SAS 4.1" do you mean Enterprise Guide 4.1? SAS versions nowadays are typically 9.1.3 or 9.2.
Assuming the statements above, the format in question was created in a specific format catalog in a SAS library. To apply it within a task in EG 4.1, SAS would need to know where to find the format, then you could select it easily from "User Defined" in the list of formats. More info on how SAS can be told to find the format is here: http://support.sas.com/kb/37/332.html
You can also see an example of applying a format in the Enterprise Guide tutorial. With Enterprise Guide started, select Help / Getting Started tutorial. There's an example of applying a format in the Query Builder under "Add a Computer Column to the Query" in screen 3 of 4.