Wikipedia:Avoid negative claims

Negative claims are statements that assert the non-existence or exclusion of something. Negative claims are assumed to be true so long as no evidence is presented to prove the claim false. Negative claims may have a positive counterpoint that asserts the existence or inclusion of something and which requires evidence to verify that the claim is true.

Negative claims, verifiability, and the burden of proof
Wikipedia's policies requires that all content must be verifiable and places the burden on the editor adding the content to demonstrate its verifiability. However, certain negative claims depend on the absence of reliable sources to assert their validity, these claims shift the burden from the editor adding the claim to the editor challenging the claim. Negative claims that can be attributed to a reliable source does.

Examples of negative claims to avoid

 * "It is unknown if ..."
 * "X has not been (fully) released in Y language"
 * "No announcement has been made ..."