It is clear, thank you. But for my example with CuFeS2 standard and Cu, Fe elements (both for LIF, channel 5) I need to collect WS for the CuFeS2 standard two times: 1 for Cu and 1 for Fe (and several times more if I want to use this channel for extra elements).
Instead, if we will have possibility to add extra element to the WS, we can collect the WS for the CuFeS2 standard just 1! time and then add any element for analysis of BG, peak overlapping effect etc.