What is the significance of "JUL" in the COMPUTE function used in FILTER clause?

@COMPUTE

I'm trying to filter data in the replicat to allow only for transaction dates greater than OCT 01 2013.

I referred the document How to Filter Records by Date in Oracle GoldenGate Extract and Replicat (Doc ID 1458966.1).

It has an example similar to below:

Replicat:

MAP {source table}, TARGET {target table},
FILTER (@COMPUTE (@DATE("JUL", "YYYY-MM-DD", creation_time) >=
                              @DATE("JUL", "YYYY-MM-DD", "2012-01-01")) > 0);

I'm trying to understand what is the "JUL" doing in the @DATE function. The above example filters data only if creation_time >= 2012-01-01.

Thanks

Hari