When you create an index of type CTXRULE, you must use the MATCHES operator to classify your documents. The CTXRULE index is essentially an index on the set of queries that define your classifications.
For example, if you have an incoming stream of documents that need to be routed according to content, you can create a set of queries that define your categories. You create the queries as rows in a text column. It is possible to create this type of table with the CTX_CLS.TRAIN procedure.
You then index the table to create a CTXRULE index. When documents arrive, you use the MATCHES operator to classify each document