Hello,
Importance: This number is used only in a merge and only when the "Weight by importance" button in the Merge menu is checked. It's intention is to allow user-specified weights in a merge. If you trust one data set twice as much as another, the more trusted one might be given an importance of 2 while the other is given an importance of 1. This was in response to a feature request -- personally I am not clear how would know how to weight different data sets.
Oh, that's why it is called 'importance'. I actually used it for a different purpose: I have experimental data of an unknown sample but suppose it contains iron and probably iron carbide. I loaded experimental data for iron foil and iron carbide (I took the latter from the Newville-database - thanks for that ressource!) and merged them in chi(k). I used the 'importance'-factor for weighting the experimental values to reflect different concentrations. This should usually be done using Artemis - but I do not know if there exist crystallographic data for iron carbide, so that was the only way to simulate a mixture I could think of. Actually the comparison of the merged dataset with my unknown sample was not very good. Which might be explained by the fact I do not have a mixture of these substances. Or is there anything fundamentally wrong with what I was doing?
Edge step:
This does not appear to be working, if I check "Fix Step", enter a value into the edge step window, and then recompute the background, the value of the edge step reverts back to the automatic value.
I can affirm that bug: the edge step is not fixed just by choosing the 'fix step'-box. Work around: first click on one of the arrow buttons which will automatically enable 'fix step'. Then you can enter a value for the edge step which will now be fixed correctly. Cheers, Gerrit