What ISO 17100 Asks For
The translation quality standard is not about language. It is about process — who touches the text, when, in what sequence, and what gets written down.
The standard specifies qualifications, a second qualified person revising the whole text, and records — because the failure it exists to prevent is physical.
A Standard Built Around a Failure Mode
ISO 17100 is the International Organization for Standardization's specification for translation services. It replaced EN 15038, the earlier European standard, when it was published in 2015, and its logic is simpler than its reputation suggests. The standard exists because translated text gets used — on labels, in operating manuals, in legal instruments, in regulatory submissions — and when it is wrong, something physical can follow. A mistranslated drug dosage, a mislabelled safety control, a procedure with its steps in the wrong order: the standard's architecture is shaped by the possibility of consequences like these.
The mechanism ISO 17100 uses to prevent such failures is not a quality score or a readability metric. It is a process requirement. Specifically, it requires that two separate qualified persons handle every translation: one to produce the target text and a second to revise the entire output by comparing it against the source. Those are different jobs, and the standard treats them as such.
The Qualification Requirement
Before the standard reaches process, it specifies who is allowed to do the work. A translator working under ISO 17100 must hold one of a defined set of qualifications: a degree in translation, or a degree in any field combined with two years of documented professional experience, or five years of documented professional experience without a degree. These are minimum thresholds, not endorsements — the standard sets a floor, not a ranking.
The qualification rules apply equally to the reviser. That person must independently meet the same thresholds and must not be the translator who produced the text. This exclusion is not procedural pedantry. The point is cognitive: a translator reviewing their own output reads what they intended to write, not what they actually wrote. Errors survive self-review at a rate that independent review substantially reduces. The ISO 17100:2015 standard is explicit that revision is a comparison of target text against source text, conducted by a qualified second person.
Revision by a second translator is not proofreading; it is a comparison against the source, line by line. Somebody else reads it first
The standard also covers other roles that may appear in a project: post-editors of machine-translated content have their own qualification path under a separate specification (ISO 18587), and project managers, though named in ISO 17100, are not required to hold translator qualifications. But the two central roles — translator and reviser — carry the full qualification requirement.
What Revision Actually Is
The word revision has a precise meaning in the standard that is different from its everyday use. Revision is not proofreading. It is not a check for spelling or grammar. It is a structured comparison of the target text against the source text, conducted to assess whether the translation is fit for its stated purpose and consistent with the domain and terminology specified by the client. A reviser who only reads the target text without reference to the source is not performing revision in the ISO 17100 sense, regardless of how carefully they read.
The distinction matters because the failure mode revision is meant to catch is not always visible in the target text alone. A sentence that reads fluently and correctly in the target language may nonetheless be a mistranslation — an omission, a numerical error, a shift in meaning that leaves no grammatical trace. Only comparison against the source catches these. What revision requires and how it differs from proofreading is a discipline with its own logic, and the standard treats it as such.
The instructive failures are the ones where a translated procedure inverted two steps, which is why this trade has a standard at all. A step in the wrong order
After revision, the standard permits a further step — proofreading and any other agreed services — but these are additional, not substitutes. The revision requirement is not optional and cannot be discharged by a more thorough proofreading pass.
The Records Requirement
The third structural element of ISO 17100 is documentation. The standard requires that translation service providers maintain records demonstrating that each step was carried out, by a qualified person, in the correct sequence. This means records of translator and reviser qualifications, records of project steps, and records of any review comments and how they were resolved.
The records requirement is where the standard connects most directly to liability. If a translated label causes harm and the question is raised in a legal or regulatory context, the ability to show that ISO 17100 was followed — that a qualified reviser compared the target text to the source, that the project steps were logged — is not merely a business benefit. In industries where translation error can constitute a regulatory breach, process documentation is a material fact. The European Commission's Directorate-General for Translation, which manages translation at an institutional scale across all EU official languages, operates within frameworks that similarly require documented process rather than relying on output quality alone.
The standard does not prescribe how records must be stored or in what format — that is left to the provider. What it specifies is that records must be retainable and retrievable. A project where steps were demonstrably performed but not recorded does not satisfy the standard.
The mechanism ISO 17100 uses to prevent such failures is not a quality score or a readability metric
What the Standard Does Not Do
ISO 17100 does not assess translation quality directly. It cannot: no standard can read a text and determine whether it is good. What it can do — and does — is specify the conditions under which quality is statistically more likely to result. A qualified translator, checked in full by a qualified reviser comparing target against source, producing documented records, is more likely to deliver accurate output than a process without those elements. The standard is a bet on process over inspection.
This is why terminology management — the practice of deciding that within a document set one concept has exactly one name — is compatible with ISO 17100 and supports it, but is not itself specified by it. Term bases, style guides, client glossaries: these sit upstream of the process the standard describes. ISO 17100 takes those inputs as given and governs what happens next.
The standard is voluntary. No law requires a translation provider to hold ISO 17100 certification. But procurement specifications in pharmaceutical, medical device, aerospace and legal contexts increasingly name it, which makes voluntary in practice a narrower category than it sounds.