International standard specifying marine fuel grades — distillates (DMA, DMB, DMZ) and residuals (RMA, RMB, RMD, RME, RMG, RMK).
In practice
Every BDN states the ISO 8217 grade and the supplier's compliance values. Operator's combustion-test lab compares against the BDN; out-of-spec deliveries trigger Letter of Protest and supplier dispute.
Regulatory detail & full definition
International standard specifying marine fuel grades. The current edition is ISO 8217:2017 with clarifications in ISO 8217:2024. Distillate grades are DMA, DMB, DMZ; residual grades are RMA, RMB, RMD, RME, RMG, RMK at increasing maximum viscosity. Specifications cover sulphur, density, viscosity, flash point, micro carbon residue, ash, water, vanadium, sodium, aluminium plus silicon, used lubricating oil indicators, and stability/compatibility. Fuel suppliers state grade in the bunker delivery note; engine builders specify the grade range their engines accept.