The empty set is always a subset.

!|Subset Query:duplicate rows|A|
|x                             |

Complete set is a subset (we do not mean proper subset).

!|Subset Query:duplicate rows|A|
|x                             |
|SuiteChildOne.SuiteSetUp      |
|SuiteChildOne.TestOneOne      |
|SuiteChildOne.TestOneTwo      |
|SuiteChildOne.SuiteTearDown   |
|SuiteChildOne.SuiteSetUp      |
|SuiteChildOne.TestOneThree    |
|SuiteChildOne.SuiteTearDown   |

Only some of the rows (in different order) form a subset.

!|Subset Query:duplicate rows|A|
|x                             |
|SuiteChildOne.TestOneTwo      |
|SuiteChildOne.SuiteTearDown   |
|SuiteChildOne.SuiteSetUp      |
|SuiteChildOne.TestOneThree    |