What is the significance of the exclamation mark (!) on ACARS page of a Boeing 737? For a while now I've noticed an exclamation mark on the ACARS inflight page of the B737NG at the beginning of a flight. It is located in the top left corner of the page and it just disappears after a while. I've been searching high and low what it means but can't find it.
Any ideas?
Okay guys, the verdict is in.

It is a symbol to indicate the crew alerting chimes are inhibited.
From OUT (off block) until OFF+15 and estimated ON-10 until IN (on block) the chimes to alert for new data and messages are suppressed to avoid nuisance warnings during critical flight phases.

Happy landings!