TI-API: About COW (Change Order Window)

Tool/software:

Dears,

According to the Backlog API business guidebook:

d. API order change requirements
…
ii. Period for order changes or cancellations
…
Change Order Window (COW) is defined as the period during which changes or cancellations are no longer authorized for processing.
…
STD (Standard) COW: 30 days
Non-STD (Non-Standard) COW: 90 days
…

Additionally, in the backlog-order-management-api.yaml document, we can see:

…
responses: '200': description: Request processed successfully.
…
cancellationWindowWeeks: 5
rescheduleWindowWeeks: 5
…

My questions are:

1. Does Non-STD (Non-Standard) include Custom (CST) or is it the same as Custom (CST)?

2. How many days are cancellationWindowWeeks: 5 and rescheduleWindowWeeks: 5?

    Do they refer to the 30 days of STD (Standard) COW, or do they mean 7 days * 5 weeks = 35 days?

My users hope for precise information on the last allowable modification date. Therefore, I plan to calculate it using

    estimatedShipDate – COW days = LastAllowedModificationDate.

However, I am unsure whether the COW days should be based on the product category (STD: 30 days or Non-STD (or CST): 90 days)
or if it should be derived from cancellationWindowWeeks: 5 = ? days and rescheduleWindowWeeks: 5 = ? days. 
How many days are these exactly?

I appreciate your guidance on this matter.