The base symbols are set up as follows: 

Using the S&P 500 March 2005 contract

/SP for the S&P 500
(S) Session - table below  (March Day = H)
(Y) Year - use last digit of the year (2005 = 5)
Completed symbol is:  /SPH5

The only exception are the E-Minis that always use the Evening Session letter.

Symbol	Definition
/ES(S)(Y)	S&P E-Mini
/SP(S)(Y)	S&P 500
/NQ(S)(Y)	Nasdaq E-Mini
/ND(S)(Y)	Nasdaq 100
/DJ(S)(Y)	Dow Jones Industrial Average (Market Session)
/ZJ(S)(Y)	Dow Jones Industrial Average (European Session)
/US(S)(Y)	Bonds

 

Month	Day Session	Evening Session
January	F	A
February	G	B
March	H	C
April	J	D
May	K	E
June	M	I
July	N	L
August	Q	O
September	U	P
October	V	R
November	X	S
December	Z	T

Examples:

  /EST5 - S&P E-Mini (Market and Evening Sessions)
  /SPZ5 - S&P 500 (Market Session)
  /SPT5 - S&P 500 (Evening Session)
  /NQT5 - Nasdaq E-Mini (Market and Evening Sessions)
  /NDZ5 - Nasdaq 100 (Market Session)
  /NDT5 - Nasdaq 100 (Evening Session)
  /DJZ5 - Dow Jones Industrial Average (Market Session)
  /ZJZ5 - Dow Jones Industrial Average (European Exchange Session)
  /USZ5 - Bonds