In accordance with the quality assurance team, we have chosen to use the same test specification design for all the projects manage within our instance of TestLink. This design matches the level of tests defined by ISTQB.
When you write your test specifications, please follow the principals enounced below:
Below is an example taken from Gazelle HL7 Validator test project.
Attached is an XML export of the basic test specifications that you can import into your project as a basis for your test specification writing. Also available here.
For the "System testing" test suite you can save time by using a feature from TestLink. In the Requirements page, for each section, you have a button named "Create Test Cases". You will be asked to select the requirements for which you want to generate test cases and then a new test suite will be created in your Test Specification. You only have to drag and drop the newly created test suite to the "System testing" test suite and complete the test cases.