.NET Framework 4.6 and 4.5
abstract Keys : ICollection with get
override Keys : ICollection with get
The order of the keys in the ICollection is unspecified, but it is the same order as the associated values in the ICollection returned by the Values method.
The returned ICollection is not a static copy; instead, the ICollection refers back to the keys in the original Hashtable. Therefore, changes to the Hashtable continue to be reflected in the ICollection.
Retrieving the value of this property is an O(1) operation.
Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1
.NET Framework Client Profile
Supported in: 4, 3.5 SP1
Supported in: 3.0, 2.0, 1.0