In metrological terminology, a "measurement standard" for ethyl alcohol. A CFS scientist who is being cross-examined should be willing to admit the metrological definition. If a bottle or canister of (what police and lawyers call) alcohol standard really is a standard, then it must fit the metrological definition. See also "traceability". Defence lawyers in Ontario may find it useful to cross-examine breath techs about the continuity of the clear liquid in the wet-bath simulator used on a subject test. If that particular breath tech is not the police officer who last changed the alcohol standard, then whatever they say about the identity of the clear liquid is hearsay. It may be reliable hearsay if there is good documentation of continuity of that clear liquid in an Alcohol Standard Log and/or an alphanumeric police seal ON THE SIMULATOR. Writing a note onto a random plastic bottle lefy on the desk or writing a note on a whiteboard or blackboard is not very good evidence of continuity of that clear liquid. Many breath techs may come and go between the solution change date and the subject test date. Some of them in that interim may use the simulator and clear liquid for another purpose e.g. calibration checks on ASDs. In some other provinces dry gas/air gas is used as an alcohol standard. In dry gas provinces is there an alphanumeric seal used between the dry gas cannister and the regulator attached to the evidentiary breath instrument?