Missing or empty fields are not populated as empty and result in global BOM scrambling.

[ghost]

Suppose you have a board with four parts: C1 (GCMxyz), D1 (BAS20), R1 (CRCWxyz), U1 (STM32F0).

You do not specify the MPN of D1 for whatever reason. Or, perhaps D1 is a DNI and has no MPN assigned.

If you group by MPN alone, KiBoM will generate a BOM with errors.

Expected BOM:

Line item	MPN	References
1	GCMxyz	C1
2		D1
3	CRCWxyz	R1
4	STM32F0	U1

Actual BOM generated:

Line item	MPN	References
1	GCMxyz	C1
2	CRCWxyz	D1
3	STM32F0	R1
4		U1

You might hope that it leaves the unpopulated fields blank, rather than zero or (-1) length, but it does not. This off-by-one error can be ultra-subtle or even unnoticeable yet cause a board to be assembled completely wrong. If you have two MPNs on the same board that are the exact same value and package but different voltage rating, you could end up with a 16V capacitor installed in the place of a 50V capacitor.

[SchrodingersGat]

@phansel in my initial investigation I am unable to replicate this.

Can you please provide a set of files as a minimal example?

• Kicad schematic file
• bom.ini configuration file
• command you are running to generate the BOM
• version of KiBOM

[ghost]

I'll prep a set of demo files.

[ghost]

Unable to reproduce this. :+1: