GCSE Writing A5 (a) Use tone, style and register for different forms, purposes & audiences
GCSE English Language: Writing
A5 (a) Communicate clearly, effectively and imaginatively, selecting and adapting tone, style and register for different forms, purposes and audiences.
Source: DfE (2013), English Language GCSE subject content and assessment objectives.
https://www.gov.uk/government/publications/gcse-english-language-and-gcse-english-literature-new-content