Assessment practice for petroleum products: second check allowed with valid PTR; otherwise first check with mandatory lab testing. Revised assessment practice for petroleum imports under CTH 27101960 and 27101990: manufacturer importers who are actual users with an overseas manufacturer supplier and a valid PTR may obtain final assessment on second check where manufacturer and supplier credentials and PTR details are uploaded to e sanchit. Manufacturer importers with non manufacturer foreign suppliers may obtain provisional second check assessment with samples sent to DYCC/designated laboratory if a valid PTR is uploaded and declared. All other cases, including non manufacturer importers or lack of valid PTR, require first check assessment with mandatory laboratory testing.