What Is ISO 18587?
ISO 18587 is an international standard describing requirements for machine translation post-editing: the process itself, and the competencies of the people who perform it. The standard emerged in response to MTPE becoming a widespread service category on its own — before it existed, clients and providers often disagreed about what "post-editing" even meant and how it differed from ordinary editing of a human translation.
Full and Light Post-Editing
The standard formally distinguishes two levels:
- Full post-editing — the result must be indistinguishable from a quality translation done by a human from scratch: correct grammar, terminology, style, and coherence
- Light post-editing — the goal is only that the text is understandable and accurate in meaning, with no requirement for stylistic polish
The distinction matters for planning: light post-editing is faster and cheaper but isn't suited to text an end client will see as a finished product — marketing material, public-facing documentation.
Requirements for a Post-Editor
ISO 18587 describes not just the process but who should be performing it: professional-level command of both languages, an understanding of machine translation's specific error patterns (which differ from a human translator's typical mistakes), and the judgment to decide when it's simpler to rewrite a segment from scratch than to edit the existing machine output.
ISO 18587 and LQA
Post-editing under the standard is a distinct production step, and LQA is a subsequent check of its output. Compliance with ISO 18587 in the post-editing process doesn't remove the need for LQA on text where a mistake is costly — the standard sets a floor for the process, not a guarantee of a specific result for every segment.
How ISO 18587 Relates to ISO 5060
ISO 5060 describes translation quality evaluation in general, regardless of who produced the text or how. ISO 18587 is a narrower, process-specific standard just for the post-editing stage. Text that's been post-edited under ISO 18587 can — and should — still be evaluated afterward against criteria compatible with ISO 5060.
FAQ
Is compliance with ISO 18587 required to use machine translation?
No, it's a voluntary standard. Companies use it as a quality benchmark for the process, not as a legal requirement.
How is full post-editing different from light post-editing in practice?
Full aims for a result indistinguishable from a human translation done from scratch. Light aims only at comprehensibility and semantic accuracy, without attention to style.
Does a post-editor need special training under ISO 18587?
The standard describes the required competencies but doesn't introduce mandatory certification — an organization decides on its own how to confirm a post-editor meets them.
Does ISO 18587 apply to post-editing LLM output?
The standard was written primarily with earlier machine translation systems in mind, but its principles — distinguishing levels of post-editing, requiring specific competencies — apply just as well to working with LLM output.
Does compliance with ISO 18587 guarantee good translation quality?
No — the standard describes a process, not a guaranteed result; final quality still needs checking, for example through LQA or QE methods.