Formula in Summary in External BOM

[Bertievz]

In our external BOM lists, we have a column for paint area, but we don't want the paint area of Grating objects to be included.  I was able to use a conditional statement to show all individual Grating parts areas as zero, while still showing the correct areas for other parts.

But.. in the summary and the total at the bottom, it still adds up all the areas including grating.  How do I tell it to only sum the non-grating items?

[bigcarl5000kg · Accepted solution]

create separate BOM for gratings only

[Bertievz]

Okay, I had a suspicion that we would be forced to use separate lists, but I was hoping that there was another way. Thank you.

[Sebastian_Eiche · Accepted solution]

As another idea:don't use the paintarea to be shown. Maybe you instead of this you use a formula: quantityxpaintarea and in the groupheader you summarize the formula itself. 
So if you use qunatityxpaintarea and the paintarea is zero, the result should be zero and therefore the summarize should correct (but look not good by having so much "zero" in it). 
I would also prefer to use to different lists

[Bertievz]

Thank you.  I don't have a very good understanding of how the summarize fields work and how to apply formulas to them, but I will try and see if I can get it to work. 

[Bertievz]

Can you tell me how to summarize the formula itself in the groupheader? Currently the groupheader's field is "../MUnitPaint" but what does that mean? How do you tell it what to add together in the group header and also in the total at the bottom?
In the detail section, I had to type my conditional statement directly in the Datafield box, so I don't know if I can refer to that formula again in the group header.
I have looked and searched everywhere for information but can't find any documentation or help on this part of the BOM editor.