What an official exchange rate is, and is not
Eleven currencies, each from the central bank that publishes it, each carrying that bank's own description of what the rate is. Brazil publishes a PTAX closing rate, Argentina a reference rate, Colombia a representative market rate, Mexico the FIX. Those are not four names for one thing, and the difference is on the page beside each number rather than flattened into the word 'official'.
An official rate is what an authority published. It is not what anyone transacted at, it ignores a depeg while one is happening, and where a parallel market exists it can sit a long way from the price people actually pay. That distinction changes what an Argentine figure means more than it changes a Brazilian one.
These are NOT the rates the dollar figures elsewhere on this site are built from. Those still come from a market series of unrecoverable provenance, which sits more than 5% away from the official rate on 13.1% of Brazilian days and 89.5% of Argentine days. Migrating the rest of the site onto these rates is separate work and has not been done.
Every currency but the Colombian peso publishes on business days only, so the intervening calendar days carry the last published rate forward. That is why a line here is drawn solid where the bank published and dashed where the rate is being held: a flat weekend is not evidence the currency did not move. Of the days published, Brazil carries 4,787 and Chile 5,107, while Colombia carries none at all because its source asserts its own weekend validity.
Where a carry reaches seven days the row is dropped rather than published. At that point the number no longer means the rate was held, it means the series stopped, and drawing it would put a flat line across a hole.
Rates are published as US dollars per unit of local currency, the same direction the site's older FX dataset uses, so the two never disagree about which way a rate points. The conventional reading — pesos to the dollar — is the reciprocal of that single published number, and the page lets you switch between them.
The series are emitted from 2021. They reach back as far as 1982, and publishing the whole span would be about 3.9 MB of artifact for one dataset. On-chain transfers begin in March 2021, and this dataset exists to price them.
Attribution is composed per leg and rendered exactly as written. Brazil's PTAX is ODbL 1.0 and Colombia's TRM is CC BY-SA 4.0, both share-alike licences whose application to published aggregates is an open legal question. The Argentine leg ships under the BCRA's own legal notice on a recorded decision. Eight legs arrive through an open-source aggregator and are attributed to the originating central bank with their terms unverified.