conjunctions - Can sentences be joined when we need to say "such as X OR Y"?

When defining something, it can also be defined, for example, as A or B. If I give you a practical case to this situation,

1. The idea behind the process is to find a common envelope.


2. The envelope should be going through the longest line’s outer end.
   or


3. the envelope should accommodate all the lines’ outer ends on to that.

then, how can the above be defined by a single sentence? Can anyone suggest a way to join all three sentences into one?