You can use %subarray buil-in function in order to do what you want to. This function is for accessing part of an array. You know that the indicator data structure can be handle as an array, then you can say:
%Subarray(*IN:70:6) = *On; (Free Format)
It means: “Turn on 6 indicators starting with 70th”.
In fixed format you just have to put this code in the factor 2 with an EVAL operation Code.