In this work, the problem of open faults affecting the inter-connections of SC circuits composed by data-path and control is analyzed. In particular, it is shown that, in case opens affect control signals, some problems may arise even if both control and data-path signals are concurrently checked. In particular, wrong codewords may be generated at the outputs of multiplexers and registers. To address this problem, new registers and multiplexers are proposed which allow the design data-paths which are TSC with respect to opens (and resistive opens). These components are also TSC with respect to stuck-at, transistor and gross delay faults. They present a good testability with respect to resistive bridgings.