An addition error mostly arises from good intentions: the translator wants to help the reader, opens up an unclear point, completes a piece of information they see as missing. Yet every added expression counts as content of the document and ends up saying something that is not in the source.
Definition
It is information that is not in the source appearing in the target text. The scope widens. The document has been changed.
Well-meant explanation
The wish to help the reader produces additions. The intention is good, the result is an error. The limit is kept.
Resolving ambiguity
Ambiguity in the source is not cleared up through translation. The authority to clarify does not lie with the translator. The situation is reported.
Adding explanatory wording
Squeezing an explanation into the sentence is a common tendency. That explanation counts as document text. The method is wrong.
The right method
If an explanation is needed, it is given as a translator's note and set apart visually. The note is separate from the document text. The separation is preserved.
Form of the note
The note is shown in brackets or as a footnote. A note that is not set apart counts as an addition. The form is applied consistently.
Completing information seen as missing
Information that is not in the source is not completed. The gap is reported. The decision is the client's.
Strengthening
Rendering a statement as more definite or stronger counts as an addition. The modality has changed. Fidelity is broken.
Softening
Weakening a statement falls into the same category. The scope narrows. Both directions are errors.
Multiplying repetitions
Repeating a warning that occurs once in the source counts as an addition. Emphasis comes from the source. The structure is preserved.
Adding conjunctions and transitions
Conjunctions added for fluency can set up a logical relationship. A causal link that is not in the source arises. Care is needed.
Setting up a causal link
A cause relationship set up between two sentences is an addition if it is not in the source. The relationship is an interpretation. The limit is kept.
Numeric addition
Rounding or unit conversion is an addition. The value has changed. The rule is strict.
Effect in legal texts
A single added expression can give rise to an obligation. The consequence is legal. Severity is high.
Effect in technical texts
An added step can misdirect the user. A safety risk arises. Severity increases.
Not to be confused with transcreation
In transcreation the freedom rests on the translation brief. There, addition is not an error. The scope is different.
Writing down the scope decision
If freedom is to be given, it is given in writing. Freedom that is not in writing cannot be assumed. The rule is applied.
Detection method
Comparative reading catches this type too. Extra elements are looked for in the target text. The method is the same.
Why good intentions are no defence
The party reading the document cannot know that a sentence absent from the source was added by the translator; they take it for content of the document and decide accordingly. That is why good intentions do not change the outcome. The limit is strict for this reason.
Limits of measurement
Mandatory explicitation required by the language does not count as addition. There are structural differences between two languages. The assessment belongs to the expert.