FormatCondition.TextOperator (Excel)
Returns or sets one of the constants of the XlContainsOperator enumeration, specifying the text search performed by the conditional formatting rule. Possible return values are xlBeginsWith - Begins with a specified value, xlContains - Contains a specified value, xlDoesNotContain - Does not contain the specified value, xlEndsWith - Endswith the specified value.
ActiveCell.FormatConditions(1).TextOperator = xlBeginsWith