Cathay Pacific non rev dress code

I will be purchasing a ZED fare on Cathay Pacific for a backup to get out of Hong Kong.

I believe it states dress code is business casual. So, what is the minimum for business casual?
I doubt jeans, tennis shoes and a polo shirt will do.
Get a little spoiled with Delta, and now United, allowing jeans, tennis shoes and t-shirts.
Will dress shoes, slacks and a polo shirt work or do I need a button up shirt.

Thanks for any information.

Tony

"If travelling on an Economy Class ticket ID passengers must also be well-groomed, neat and clean in appearance. Please remember that whilst ID passengers may wear clean and tidy denim jeans (i.e. not torn or frayed), they will not be upgraded unless they are able to change into more formal attire. ID passengers will not be accepted for travel in Business or First Class if wearing denim jeans."

You won't get an upgrade anyways, jeans OK

We (and our "friends&family") Always travel business casual...sport coat etc. Where else would you keep your passport/tkts/etc.

Thanks everyone for the information

Tony