In a GuiXT script we work with the command "On" to define our own handling for certain function codes like "/3", "/12", "/15". The 3 InputScripts are almost identical and we would like to avoid the redundant coding involved. Is there a way to achieve this?

The "using" command is available for "On" as well, e.g.:

On "/3" "process=IS_return.txt"
using FC = "/3"

On "/12" "process=IS_return.txt"
using FC = "/12"

On "/15" "process=IS_return.txt"
using FC = "/15"

In the InputScript you then work with a parameter "FC", e.g.:

Parameter FC
...
Enter "&U[FC]"