A method to allow a value to be written into one PCR domain, only if values from a second PCR domain are valid, thus ensuring the extension of the chain of trust between domains. The system includes a system bridge, a host module including a central processing unit coupled to the system bridge, a scalable serial bus coupled to the system bridge, a client controller coupled to the system bridge via the scalable serial bus, and first and second clients coupled to the client controller. The cross section of the injection probe is substantially smaller than the rear opening of the speculum, so that the monitoring of the optical effects provoked to the tissue by the marker and the insertion of treatment tools is not obstructed. The thermoelectric switches operate such that an on state is defined as heat flow being allowed by virtue of the thermal conductivity of the thermoelectric switch. A plurality of directories is located in the hierarchal file system.