This keyword will always occur after a trailing slash and can include query parameters. It will return the total record count (with respect to the supplied query parameters).
GET http://restapi.lucity.net/gbaMS/Work/WorkOrders.svc/$count
GET http://restapi.lucity.net/gbaMS/Work/WorkOrders.svc/$count?Filter=WKORDER+WHERE+WO_STAT_CD%3C950
GET http://restapi.lucity.net/gbaMS/Work/WorkOrders.svc/MainTaskCode/$count