Glossary

The words these docs and the admin use, defined once.

YMMS

Year, Make, Model, Submodel. The four-level cascade the app uses to identify a vehicle. Every vehicle in the taxonomy resolves to a numeric vehicle_id; widgets pass that ID around, never the strings.

Submodel

The trim or variant level: Lariat, Rubicon, TRD Off-Road, Si. A mapping with the submodel left blank applies to every submodel of that year, make and model.

Vehicle ID

The stable numeric identifier for one exact YMMS combination. What actually gets stored on a product document and compared at query time.

Fitment source

Anywhere a SKU-to-vehicle claim comes from: tags, CSV, Sheets, metafields, a vendor feed, the WySync data add-on, or the editor.

Union

The merge rule. A SKU fits a vehicle if any connected source says so. No precedence, no winner.

Overlay

An editor change applied after the union: an addition, an exclusion, a universal flag or a note. Survives every reindex.

Universal

A SKU that fits everything: cleaner, a universal hitch pin, a torque wrench. Flagged rather than mapped, and never filtered out by a vehicle.

Verdict

The answer shown to a shopper: fits, does not fit, or unconfirmed. Copy is yours; the three states are not.

Envelope

A range of acceptable values for a vehicle rather than a single number — diameter 17"–24", offset −24 to +45mm, lift height 4–6". Real fitment is ranges, which is why exact-value matching produces so many false negatives.

Bolt pattern

A wheel term: number of studs × the circle diameter, e.g. 6x135. Canonicalised on ingest so 5x114.3, 5×114.3mm and 5x4.5" are one value. Listed here because it's the canonical example of a value with many spellings.

Hub bore

The centre hole. A wheel's bore must be at least the vehicle's hub diameter; a larger bore is fine with a hub ring, a smaller one cannot physically seat.

Offset

How far the mounting face sits from the wheel's centreline, in millimetres. Positive tucks the wheel in, negative pushes it out.

Aggressive fit

Physically mountable but outside the stock envelope — the stance-oriented answer. A distinct verdict tier, not a silent yes.

Spec field

A typed product attribute in the index (spec_num_*, spec_int_*, spec_str_*, spec_strs_*, spec_bool_*) mapped from your metafields. Works for any attribute — blade length, pad compound, hitch class, lift height — not just wheel measurements. Drives facets and, for wheels and tires with the add-on, spec matching.

Normalization

Turning many spellings of one value into one canonical value. Physics rules ship in code; brand and make synonyms are per-shop and editable.

Indexing job

One run of the indexer, logged with a status, counts and any per-product errors. Visible under Indexing.

Reindex

Rebuilding the whole index from Shopify. Run it after connecting a source or changing a metafield mapping.

App proxy

Shopify's mechanism for letting your storefront call an app over your own domain, HMAC-signed. Every widget request goes through it.

Theme app extension

The packaged blocks and assets Shopify hosts for the app. What you add in the theme editor; it never touches your theme's own files.

App embed

An extension block that loads globally rather than in one section. WySync's bootstrap embed carries the shared vehicle state.

Mapped collection

A collection you've chosen to show on the post-vehicle-search landing page. Does not affect which collections get a fitment-aware grid — that's all of them.