Testable statement vocabulary in the Wiki

I am confused about the vocabulary being used in the test wiki:

https://www.w3.org/wiki/ARIA_1.1_Testable_Statements#scrollbar <https://www.w3.org/wiki/ARIA_1.1_Testable_Statements#scrollbar>

1. For IA2, UIA, and ATK why do we have have contains when referring to the value of a structure attribute?

e.g.: 
AccessibleValue.minimumValue contains 0
RangeValue.Minimum contains 0

The property does not contain anything it IS a value

I understand it for interfaces but this makes no sense. 

2. Also, what is the appropriate way to specify UIA Patterns?

property Selection Pattern  is <shown>

vs. 

property Interfaces contains Selection Pattern  


We just don’t seem to be consistent. Property values are property values they don’t contain anything. Contain means that you can have 0 or more of something: Patterns, interfaces, etc. 

I will put in what you want but what is there seems counterintuitive. 

Cheers,

Rich