(for context, g/pal4.bmp is a "Paletted image with 12 palette colors, and 4 bits/pixel.")

• g/pal4.bmp exactly but with biClrUsed set to 13, so the color palette is expected to contain 13 entries, but it actually only contains enough bytes for 12 entries
• g/pal4.bmp exactly but with biClrUsed set to 0, so the color palette is expected to contain 2^4 = 16 entries, but it actually only contains enough bytes for 12 entries

From what I've seen, both Windows and Firefox reject both of the above as invalid.

These would nicely complement q/pal8offs.bmp, which has more bytes in the palette than expected / extra bytes between the palette and the pixel data.