C90 controller reported an ord arriving aircraft on a STAR issued 'descend via' clearance descended ...

Narrative:

I was advised by the feeder sector that aircraft X checked in on the arrival descending to 4000 feet. The controller caught the target altitude upon check in and instructed aircraft X to maintain 7000 feet instead. I called ARTCC to ask what aircraft X was issued and they said 'descend via the arrival; maintain 300 knots.' I had aircraft X call so I could inquire about the error. I spoke with the captain for the flight; about how he interpreted the arrival and why his actions differed from everyone else. He apparently understood the segment altitudes to be the bottom altitude on the arrival that he could rightfully descend to after the mandatory crossing.the assortment of altitudes on the STAR seem unnecessary if the descend via only authorizes 110. However; if ZAU cleared the aircraft to descend via except cross fytte at and maintain 110; it would certainly help clear up any confusion for the occasional confused crew.

Original NASA ASRS Text

Title: C90 Controller reported an ORD arriving aircraft on a STAR issued 'descend via' clearance descended through a crossing restriction on the arrival. The reporter spoke to the pilot who did not understand how to comply with the restrictions on the approach once issued 'descend via' ATC phraseology.

Narrative: I was advised by the Feeder Sector that Aircraft X checked in on the arrival descending to 4000 feet. The controller caught the target altitude upon check in and instructed Aircraft X to maintain 7000 feet instead. I called ARTCC to ask what Aircraft X was issued and they said 'Descend via the arrival; maintain 300 knots.' I had Aircraft X call so I could inquire about the error. I spoke with the Captain for the flight; about how he interpreted the arrival and why his actions differed from everyone else. He apparently understood the segment altitudes to be the bottom altitude on the arrival that he could rightfully descend to after the mandatory crossing.The assortment of altitudes on the STAR seem unnecessary if the Descend Via only authorizes 110. However; if ZAU cleared the aircraft to Descend Via except cross FYTTE at and maintain 110; it would certainly help clear up any confusion for the occasional confused crew.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1309605
Time
Date	201511
Local Time Of Day	1801-2400
Place
Locale Reference	C90.TRACON
State Reference	IL
Environment
Light	Night
Aircraft 1
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR FYTTE3
Flight Plan	IFR
Person 1
Function	Approach Supervisor / CIC
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 6.0
Events
Anomaly	Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

C90 controller reported an ord arriving aircraft on a STAR issued 'descend via' clearance descended through a crossing restriction on the arrival. The reporter spoke to the pilot who did not understand how to comply with the restrictions on the approach once issued 'descend via' ATC phraseology.