> ## Documentation Index > Fetch the complete documentation index at: https://docs.truckaurbus.com/llms.txt > Use this file to discover all available pages before exploring further. # Comparison conventions > One basis for every maker, so two vehicles compare line by line. Makers print the same figure a dozen ways. The register keeps one form for each, and every write path holds to it: the ops desk, the import commands and the publish of an approved draft. A value that does not fit is refused at the door; it never reaches a sheet. Read the fields below with these rules and you can compare any two variants without cleaning them first. ## Seats `seating` counts the passengers only: the driver, an attendant and a conductor are left out. A maker's "D+2" is `2`, a bus's "52+D" is `52`, "Driver only" is `0`. It is a whole number from 0 to 120. The site labels it "Seats (excl. driver)". ## Tyre size `tyre_size` is one canonical headline: `[/][rim][LT|C][-PR]`, with no spaces. Inch widths under 10 keep two decimals (`7.50X16-16PR`), 10 and above are whole numbers (`10R20`); a metric size keeps its slash (`295/80R22.5`). A vehicle that runs two sizes joins them with `/` (`10R20-16PR / 295/80R22.5-16PR`). Words such as Tubeless or Radial are not part of the size. To match a size, use the `tyre_size` filter on `/variants`, which reads every spelling the same way (`7.50x16`, `7.50 X 16 -16 PR` and `7.50X16` are one size), or `/tyre-sizes` for the sizes on the register with their counts. ## Fuel `fuel` is one of `diesel`, `petrol`, `cng`, `petrol-cng` (bi-fuel), `lpg`, `lng`, `electric`, `hydrogen`, `hybrid`, or empty when the maker does not say. ## Name `name` is the maker's own name for the variant, with nothing left out and never opened by the maker's name: the maker travels beside it as `manufacturer.name`, so print the two together. A product family the maker sells under its own word stays in the name (`King Deluxe CNG`, `ISUZU NQR (CHS)`). The `slug` never changes once published. ## Body types `body_types` holds keys from one vocabulary (`chassis_cab`, `cowl`, `open_deck`, `tipper`, `container`, `school_bus` and the rest of the `body_type` facet on `/taxonomy`), at most six. A maker's own word for a body the vocabulary does not hold is not a key: it is kept on the sheet, in the maker's words, on the line "Body, in the maker's words" of the `body` group in `spec`. ## Class `vehicle_class` is the register's class: `truck`, `bus`, `pickup`, `three-wheeler`, `tractor` (the prime mover of a tractor-trailer, never a farm tractor), `tipper` or `special`. Farm tractors and construction machines are their own sections, on `/tractors` and `/machines`. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.