This field specifies the value against which retrieved variables are checked. The type of check which is done depends on the type of the retrieved variable. If the variable is numeric (INTEGER, Counter, etc.) this field is presumed to be a number, and a numeric comparison is performed using the specified threshold condition. If the retrieved variable is a DisplayString (OCTET STRING) and the 'value' keyword is used on the condition then both the retrieved variable and this field can be converted to a floating point number, a floating-point comparison is done; otherwise a string comparison is done. If the ~(LIKE) or ~=(LIKE CASE) condition is used then the value can be an extended regular expression. A value expression is also allowed to be specified. The expression can be any expression comprised of the following functions: 'Min' - lifetime minimum 'iMin' - interval minimum 'Max' - lifetime maximum 'iMax' - interval maximum 'Avg' - lifetime average 'iAvg' - interval average 'Sd' - lifetime standard 'iSd' - interval standard deviation deviation 'Var' - lifetime variance 'iVar' - interval variance 'Smpls' - lifetime samples 'iSmpls' - interval samples 'sTime' - sample time in secs 'iTime' - interval time in secs 'iRate' - rate of change over the interval The interval is defined by the MIB variable: smMlmProgramControlSamplesPerInterval. The expression has the following high to low precedence and left to right associativity of operators: () : grouping - : unary minus * : multiplication, / : division, % : remainder + : addition, - : subtraction << : bitwise left shift, >> : bitwise right shift & : bitwise AND ^ : bitwise exclusive OR | : bitwise inclusive OR Expression evaluation/operators are based on standard c program execution. For example: Avg+2*Sd is the average value over the lifetime of the threshold plus two times the standard deviation.