Confusion about when it's my navigation, and when it's ATC

On 2007-01-03, Mxsmanic wrote:
Pixel Dent writes:

I think I read this section before; this paragraph sounds familiar. I
always get instructions to "maintain," though. What's the phraseology
when I get a block of altitudes? Or does it even happen with
frequency in real life? How do I request it (or do I even need to
request it)?

From a flight today, west of Billings, MT:

N12345: Unable to maintain 16,000 for turbulence.
ATC: N12345 maintain between 14,000 and 16,000

or you can just request it directly:

N12345: Request block altitude between 15,000 and 17,000.
ATC: N12345 maintain block altitude between 15,000 and 17,000.

-Milen