Our objective is to define a test modeling language, called TTT, making it possible to express scenarios and conditional operational profiles. These conditions are variables introduced by test designers and must be defined in the test model. We have outlined the main characteristics and operational semantics of this test modeling language:

• The TTT language must support conditional probability specifications for all the CTT operators.

• The TTT language should store the “traces” of the user actions and support read-only functions on these traces.

• The TTT language should be formally defined to support automatic test generation.

• The TTT language operator semantics are defined as shown in section 4 by means of a C-like language.