MELBOURNE -- Standard & Poor's CreditWire 8/21/97 -- Standard & Poor's today assigned its double-'A'-minus long-term and 'A-1'-plus short-term ratings to Credit Union Services Corp. (Australia) Ltd. (CUSCAL). The ratings reflect CUSCAL's central role as a Special Service Provider (SSP) within the Australian credit union industry, its ample balance sheet liquidity, low asset risk, an experienced and conservative management team, and strong capital ratios. As the largest of three SSPs for Australian credit unions, CUSCAL fulfills the role of central banker in the credit union industry, providing intermediation, management of prime liquidity funds, and other financial nonintermediation services to its member credit unions, which equal 83.6% of total credit union assets. SSPs are bodies owned and controlled by individual credit