They must also be based on full legal advice from the Legal Services Department in consultation with the Counsel General, and include a proper appraisal of any financial implications.
Dylai'r cynllun terfynol hwnnw hefyd gael ei lywio gan farn arbenigwyr a barn y cyhoedd ar wasanaethau bysiau, er mwyn sicrhau ei fod yn ystyried amrywiaeth o safbwyntiau.