Black flecks, white flecks. What's the difference?

[Kit_Taylor]

Often on the same film, print damage takes the form of both black and white marks. Why the colour difference? Is it something to do with film processing?

TIA

[Richie]

I could be wrong (and will be corrected I'm sure if this is the case!) but I understand that 'black' marks are things like dust and other debris on the film print whereas the 'white' marks are usually damage to the print or negative (where the emulsion has been scratched off etc)
Richie

[Michael Brooke]

That's absolutely the reason:

black marks = dirt on the print;
white marks = dirt on the negative.