It seems that I didn't make myself clear. Well, it's not about a single Matrix combat or something. Let's say the decker used Matrix Perception to spot an important NPC and took note of her commcode, but when the decker tried to put Marks on that persona, he messed up. NPC got offline immediately, and several hours later, decker wanted to try another time. He must spot that icon first, right?
Matrix Perception shows it's possible to spot icon that's 100 meters away, but it doesn't mention specific requirement. So I have always been like, you cannot find any icon without clue of it, cuz there're so many icons on the grids. Commcode seems appropriate to be used as a clue, for though anyone could easily change their icon with a simple action, commcode seems more solid.
Besides, if commcode could not help hackers to spot the icons they're looking for, how could this work? Just roll Matrix Perception to achieve a threshhold to spot any Icon they want? It seems little bit of…… unreal. Moreover, this also means that their rivals or enemies could try to find them in the same way, right? It's a heavy-Matrix mission so I realy do not want my players to keep offline all the time.