In Testersuite a distinction can be made between test runs in which the order of executing the test cases is enforced(Maintain order = yes) and test runs in which this is not the case(Maintain order = no). Whether the order should be enforced can be set in the details of a test run.
If the order is to be enforced(Keep order = yes) then the Active tester field indicates which tester's turn it is to run its test case. In these test runs there is always one active tester.
If the order does not need to be enforced(Keep order = no) then all testers in the test run can run their tests at the same time. If the test cases in a test run have different testers then the Active tester field takes the value 'Multiple testers'. When all test cases have the same tester then this tester becomes the active tester. To determine whether there are multiple testers or a single tester, only the test cases that have not yet been completed are considered.
Example of a test run with Hold order = no
This test run has four test cases and three different testers (Janneke, Fred and Peter). All of these testers have not yet completed their tests. A test case is completed when it has the status OK or Skipped . In this example, the Active tester field will take the value 'Multiple testers'.
Fred continues testing and at some point has completed his test (test case has been given the status OK ).
From then on, all test cases that have not yet been completed will have the same tester (Peter). This means that the value of the Active tester field in this test run will change from 'Multiple testers' to 'Peter van den Berg'.
Example of a test run with Hold order = yes
This test run has four test cases and two different testers (Karin and Fred). Karin is the first tester to run her test. She has already started testing but has not finished. Only her test case can be run because the sequence is enforced. This is indicated by the hourglass 
icon. In this example, the field will be Active tester be given the value "Karin Hoppenberg.
Karin continues to test and at some point has completed her test (test case has been given the status OK ).
This means that the value of the Active tester field in this test run will change from 'Karin Hoppenberg' to 'Fred van Drummelen'. Fred will be automatically notified by email at that time that it is his turn to run his test. When Fred has finished his test case then the next test case can be run and Karin will become the active tester again. And so on.
For more information, see: Active tester