In the following formula (from SHEET2!) rather than Index just the ANSI150
array, i want to Index an array named in another cell that might be anyone of
a number of arrays names. eg I have both a ANSI150 and ANSI300 array and i
want to return the result based on which one of these is in another cell -
say B18 on the SHEET2!

=IF(A18>0,INDEX('Gasket
Calculation.xls'!ANSI150,MATCH(C18,Sheet1!$A$6:$A$26,),MATCH("iD",Sheet1!$A$6:$H$6,)),"")