This read-create INTEGER is the first of up to three ACL-pointer slots a class map can use to define which traffic it matches, pointing to a specific entry in the ACL table. An admin uses this to tie a class map's matching logic to a previously built ACL, so all the granular address, port, and protocol matching already defined in that ACL becomes the class map's traffic selector. For example, an admin building a 'VOICE' class map would set this first match slot to point at an ACL that identifies RTP or SIP traffic by port range.