There are some situations when you definitely need some way of recognizing new input from user. These are rather rare occasions, but when it’s nice to have such a tool is sack.

One of the applications was discussed in this communities topic. By the way, I’m spending much time on communities these days (it’s a very slow site, so no surprise) and I recommend it as a valuable resource for finding cognos-related answers. A steady pace of 10 topics a day gives a rather solid knowledge base now, after 4 months of uptime. If only it was faster, sigh…

So how to catch the fact that user changed this specific cell?

Simple, you just have to remember about virtual dimensions and calculation rules to build a “trigger”.

1. You add a simple dlist {value, old_value, new_value_flag}, with new_value_flag = (value?=old_value). new_value_flag is a dlist-formatted element with (yes\no) elements.
2. After user inputs new data into cell, this flag will change to yes (by IF formula) and you can use this data by writing an accumulation dlink using only new data (select yes value from new_value_flag virtual dimension).
3. When you’ve finished processing freshly inputed data, you just run another link that copies value to old_value, and that sets the flag back.

Ps: It’s too bad we didn’t follow that topic on communities to a logical end.