Definition of 'employed' as relates to eligibility for Class 2 while working abroad

Hello, I'm currently working full-time in US, and have been approved for class 2 contributions. If, in the future, I decide to work part-time, will I still be eligible for class 2 contributions. I can't find a definition of 'employed' anywhere. Thanks!

Hi,
I can confirm that you would continue to be eligible to pay at the class 2 rate even if you decided to work part time. 
You would no longer be eligible to pay at the class 2 rate if you didn’t work abroad at all. 
Thank you.