Few examples to help clarify how PeopleSoft arrays work.

Local Array of Number &MYARRAY;
&MYARRAY = CreateArray(100, 200, 300); Result is [100] [200] [300]

You can assign values to the elements of the array:

Local Array of Number &MYARRAY;
&MYARRAY = CreateArrayRept(0,3); Result is [0] [0] [0]
&MYARRAY[1] = 100; Result is [100] [0] [0]
&MYARRAY[1] = 200; Result is [100] [200] [0]
&MYARRAY[1] = 300; Result is [100] [200] [300]

Use the Push method to add items to the end of the array:

Local Array of Number &MYARRAY;
&MYARRAY = CreateArray();
&MYARRAY.Push(100); Result is [100]
&MYARRAY.Push(200); Result is [100] [200]
&MYARRAY.Push(300); Result is [100] [200] [300]

Use the Unshit method to add items to the beginning of the array:

Local Array of Number &MYARRAY;
&MYARRAY = CreateArray();
&MYARRAY.Unshift(300); Result is [300]
&MYARRAY.Unshift(200); Result is [200] [300]
&MYARRAY.Unshift(100); Result is [100] [200] [300]