Sources and methods

Theportbook provides tariff and trade information for the Asia market. Its news section sources content from the published news feeds and article indexes of specialist publications which report on tariffs, trade agreements, customs procedures and related logistics. These publications cover the core topics that form the site’s spine: the tariff line and the agreement that changes it. Each selected story is processed with automated assistance to extract the key factual developments, is rewritten into a concise summary, and is clearly credited to the original publication. If a specific trade fact or claim appears in only a single publication, it is noted as such within the summary to provide transparency on its sourcing.

The site’s factual reference pages, such as those detailing a specific trade Agreement, a Country trade profile, or HS codes, are constructed differently from its news. They are built from stable, verifiable facts drawn from official sources like legal texts, government publications, and international organisation databases. These pages feature a standardised facts table presenting core data and include a credited photograph where available. The reference information is not subject to daily change and is maintained as a structured resource.

Both the news summaries and the reference pages are regularly refreshed to maintain accuracy. News coverage is updated continuously as new reports are published by the source outlets. The factual reference pages are reviewed and updated on a scheduled basis, particularly when underlying official information changes, such as after a new trade agreement enters force or when a government amends its tariff schedule. This ensures theportbook provides current news alongside a stable core of reference material for its users.