Recital (92)
There are circumstances under which it may be reasonable and economical for the subject of a data protection impact assessment to be broader than a single project, for example where public authorities or bodies intend to establish a common application or processing platform or where several controllers plan to introduce a common application or processing environment across an industry sector or segment or for a widely used horizontal activity.
Source: EUR-Lex, Regulation (EU) 2016/679. Official text, reproduced without modification.