Hi,
Lets understand clearly what margin exactly is and how it is calculated.
Margin which is required to trade a contract is combination of 2 variables.
Span margin + Exposure margin.
Span margin is a must to trade a contract and it is generally required by the exchange in addition to that Exposure margin is also added to cushion the movement of day to day movement.
In our example Silverm the required margin is 30000 approx per lot.
If you break up the same its span is 7.5% and exposure is 5% of the contract value. (18K + 12k approx at friday's closing.)
www.sharekhan.com/Upload/Commodity_Upload/McxSpan.xls
So for positional trade one is able to hold a silverm lot with 30K(overnight holding can be buy or sell)
Now if you are talking about max 10x exposure then it applies only to Intraday trades where you might get to trade at 10 times exposure which means 30K amount will be reduced to 3000 per lot for intraday. So for intraday trading you can have 10 times as many lot as you can have versus positional trade which is only 1 lot overnight - that's the simplest way to understand it.
I doubt it if you are getting 10x exposures in commodities as they are very long discontinued by the brokers, the best one could get is 2-3 times max.