UMLR — A type defines a set member (not a set)

CURRENT
1) “A Type specifies a set of allowed values known as the instances of the Type.
2) “Depending on the kind of Type, instances of the Type may be created or destroyed over time.
3) “However, the rules for what constitutes an instance of the Type remain fixed by the definition of that Type.”

COMMENTS
1) “A Type specifies a set of allowed values known as the instances of the Type.
Surely a type does not specify a set?
Rather it specifies what it takes to one (any) member in the afore-mentioned set?
It defines each individual in a collection of instances.
Surely the sentence should be changed, perhaps along these lines?
“A Type specifies each value in the set of values known as instances of the Type.”
“A Type specifies the rules for what constitutes an instance of the Type.”
"A Type specifies features shared by things that are instances of the Type.”
"A Type specifies each member of a set by defining one or more characteristics shared by all the members of the set.”
"The set members are instances of the Type."

2) “Depending on the kind of Type, instances of the Type may be created or destroyed over time.
So there are two kinds of Type? What are they are called?

3) “However, the rules for what constitutes an instance of the Type remain fixed by the definition of that Type.”
Surely “the definition of the type” is tautologous?
The Type is the definition ­ the definition of the rules for what constitutes an instance.
Surely should be changed thus?
“The rules for what constitutes an instance of the Type remain fixed by the Type.