key to

phrasal verb
keyed to; keying to; keys to

Definition of key to

chiefly US
1 : to make (something) suitable for (a particular use or type of person) I try to key my lectures to my audience. often used as (be) keyed to The educational program is keyed to the needs of working women.
2 : to change (something) in a way that is closely related to (something else) usually used as (be) keyed to The amount of money they receive is keyed to the rate of inflation.