.DJI for Dow Jones
.INX for S&P 500
.IXIC for NASDAQ
.N225 for Nikkei 225
.HSI for Hang Seng Index
.TWII for TSEC
.FTSE for FTSE 100
.STOXX50E for DJ EURO STOXX 50
.FCHI for CAC 40
.GSPTSE for S&P TSX
.AXJO for S&P/ASX 200
.BSESN for BSE Sensex
For the german DAX you can use "DAX&x=INDEXDB".