It might be reasonable to have a separate key for "tab" vs "next field", as well as separate key for "line break" vs "send". (But, tab and line break are not applicable for all contexts.)

However, it might also be reasonable to have a key or key combination (some programs use ^V) to enter control characters as data rather than as commands.

It might also be a consideration when designing a new computer (which does not have to be the same as existing ones); I had thought about such things and may make such a consideration.