A material rated B-s1,d0 is not the same as one rated C-s2,d0, even though both sound similarly reassuring in a product brochure. The letters and numbers each carry a specific, checkable meaning.
The main classification letter
EN 13501 rates construction products from A1, non combustible with no contribution to fire, down through A2, B, C, D and E, to F, meaning no performance determined or the material fails to meet even the lowest class, based on how much a material contributes to fire growth and how it behaves when exposed to it.
This main letter is what most product literature leads with, but it is only part of the code, and reading only the letter while ignoring the additional classifications that follow it misses information that matters just as much in an actual fire scenario.
What the s and d suffixes add
The s value, from s1 to s3, rates smoke production, with s1 being the lowest smoke output, and the d value, d0 to d2, rates flaming droplets or particles, with d0 meaning none produced. A material rated B-s1,d0 produces little smoke and no flaming droplets, while a material rated B-s3,d2 shares the same base letter but performs far worse on both counts, a difference that matters enormously for evacuation visibility and fire spread.
Comparing two products by their base letter alone, without checking the s and d values, can lead to specifying a materially worse product under the mistaken assumption that a matching letter means matching performance.
Where this matters most in a specification
Escape routes, enclosed corridors, and any space where smoke visibility directly affects life safety deserve the full code checked, not just the base letter, since these are exactly the spaces where the s and d values determine how much time occupants actually have.