Rationale for revision In response to market drivers for renewable fuels, blending and use of synthetic aviation fuel and hydroprocessed vegetable oil or renewable diesel is increasing. However, neither ASTM D1655 nor ASTM D975 require reporting of synthetic hydrocarbon content. On occasion, a fuel product may need to be returned to a refinery for re-processing, typically via a crude distillation unit. Historically, this could be due to contamination or degradation of the product post-certification, pipeline interface/transmix not fit for use as a finished product, or an incorrect grade/blend supplied to a customer. As the industry moves forward with renewable fuel products, there will be a need to re-process these synthetic hydrocarbons for similar reasons as included above. The returned material may contain synthetic hydrocarbons obtained from biomass (e.g. synthetic components in D1655 jet fuel or hydroprocessed vegetable oil in D975 or EN590 diesel fuel), which is chemically indistinguishable from conventionally-derived hydrocarbons. As these synthetic hydrocarbons are re-processed within a refinery, they may distill with their conventional analogues. The current language contained within the materials and manufacture section of ASTM D1655 does not acknowledge non-conventional feedstocks except as per the current co-processing section Annex A1. This Annex however does not recognize synthetic hydrocarbons as a feedstock for co-processing. The intent of this ballot is to acknowledge the presence of synthetic hydrocarbons in streams designated for re-processing and declare these as acceptable for use in the manufacture of jet fuel. Reference is made in the draft ballot to recognize existing industry guidance (i.e. EI/JIG 1530) for managing the risk of streams returned to refineries for re-processing.