I asked our risk manager , John Thorpe:
Start and End refers to the range of contract months assigned to the particular maintenance margin requirement.
To arrive at your Initial spec requirement, make sure to multiply the maintenance req. by 110%.
I think a word of caution is in order about good faith deposit amounts set by the exchanges.
Just because the volatility scans in the deferred months are smaller, less than the "front" months, does not mean the market price for those deferreds can't swing beyond the initial margin requirement,
On the contrary, “liquidity in markets is, more than anything, a function of confidence, though that confidence is abundant now, it can evaporate in an instant.”
Please pay attention to the Open Interest and volume for any product you consider trading as the deferred markets are largely used by large commercial concerns and turn over their hedging portfolios infrequently.