Methodology

The source hierarchy

Not all sources are equal, and the ranking matters most when they conflict. In order:

• 1. Publisher and manufacturer documentation — The organisation that made the thing, describing the thing. Sleeve and holder dimensions from the manufacturer's own product listing; tournament legality from the game publisher's official rules document; submission requirements from the grading company. This is the only tier a measurement may come from.
• 2. Preservation and conservation institutions — National archives, national libraries and conservation centres, for questions about materials, environment and long-term damage. These bodies have no commercial interest in the hobby, which makes them the right authority on which plastics are safe and what 'archival' does and does not mean.
• 3. Directly fetched, indirectly reached — Some primary sources block automated retrieval or publish only as PDF. Where a claim rests on a store listing or a search result rather than a page retrieved in full, that limitation is recorded rather than glossed over.
• Not a source — Hobby blogs, forum consensus, retailer copy that names no manufacturer, and anything the writer merely remembers. None of these may originate a factual claim on this site, however widely repeated.

What happens when sources disagree

Higher tier wins, and the disagreement gets named on the page rather than quietly resolved. A reader who has seen the other claim elsewhere deserves to know why this site says something different.

The clearest case on this site is sleeve sizing for Japanese Pokémon cards. A number of hobby sources state that Japanese cards need Japanese-size sleeves. Manufacturers list Pokémon under standard size with no language qualifier, and their Japanese-size lines name only Yu-Gi-Oh! and Cardfight!! Vanguard. The manufacturers are followed, and the conflict is stated on the Pokémon sleeves page rather than left for the reader to trip over.

What happens when nothing can be verified

The claim is not published. This is the rule that costs the most content and it is not negotiable.

A worked example: whether D-ring binders damage cards less than O-ring binders is asserted constantly in the hobby. No manufacturer publishes comparative data, and no conservation body has examined it. It was therefore cut from this site entirely rather than published with a hedge, because a hedged claim still reads as a fact once it is quoted somewhere else.

Where a claim is genuinely uncertain but worth stating, it is phrased as uncertain in the text — not upgraded to a specification, and never put into a comparison table, because tables imply a precision the underlying source does not have.

Limitations worth knowing

Some primary sources cannot be retrieved in full. Several grading companies and conservation institutions block automated access to their own guidance, so a handful of claims rest on those organisations’ store listings and published summaries rather than on the full document. That is a weaker basis than a directly retrieved page, and it is tracked as such.

Manufacturer dimensions are nominal. Sleeves and holders vary by roughly a millimetre between production runs and between brands, and a figure quoted to the millimetre is a specification, not a guarantee about the item in your hand.

Nothing here is tested in a laboratory. This site reports what the organisations responsible for these materials publish. It does not run accelerated ageing trials, and it does not claim to.

Corrections and revisions

Claims that turn out to be wrong are corrected at the source, and the correction is recorded next to the copy so the same error cannot return in a later rewrite. Guides carry a last updated date.

Every page states its sources beneath the content. If a claim here does not match what its source says, the claim is the thing that is wrong.