Sustaining support question

I had a quick question concerning sustaining support. I have read the lifetime support policy and such, but one of the items that I am not exactly clear on is the level of technical support you receive while on sustaining support.

Can anyone provide a some clarification on what the impact of sustaining support is on technical support? I pulled the following from the documentation

• Sustaining support includes assistance with service requests, on a commercially reasonable basis, 24 hours per day, 7 days a week
• Sustaining support does not include 24 hour commitment and response guidelines for Severity 1 service requests as defined in the Severity Level section below

Do you still have the option to open Severity 1 service requests while on sustaining support? What are the main differences from Premier support and Sustaining support in regards to technical support? (I understand the bug fixes / CPU patch differences)

Thanks in advance

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