reached by or to be leveled by
 

What does it mean by 'by'? is it the same as 'at or before' or just 'at' in terms of ATC or aviation intentions.
We've been discussing a lot by this specifically exact meaning since almost every time it seems that Heathrow control says the word.

Many thanks.

BTW, I used to be cleared by Paris DG approach just a phraseology 'history landing' and everyone in the cockpit just turned to see each other in the faces and be hilarious how easy she was.

If ATC says "be level by XXX", I take that to mean "at or before XXX", or "no later than XXX".

Have been to CDG a few times and I know they have some different terminology. Have never heard the term 'History Landing'. Has anyone else?

I took it this way as well. but in a second thought it seemed like they mean only "at".
"by" is literally "by" anyway. many thanks for the reply.