Cities and countries reporting on this indicator are encouraged to promote better design and use of streets as public spaces. The fact that the indicator measures the share of the built-up area allocated to open space makes it sensitive to the definition of what constitutes a city and its built-up area. The indicator does not include measurement on safety, and it partially covers the notion of inclusivity by reference to access should be available "for all? Definitions on what constitutes public space, public use and the notion of open were agreed upon by experts through consultative meetings.35 Disaggregation of information by sex, age and persons with disabilities remains a key challenge which requires conducting comprehensive surveys in cities on public spaces.