The uncertainty for each reported measurement of each determinand shall be determined
following Annex E expressing the result to a confidence level of 95%. This uncertainty
determination shall follow the methodology of the law of propagation of uncertainty as laid
down in BS EN ISO 14956 and BS ENV 13005 (GUM). Many of the uncertainty sources will
be common for each determinand, and therefore much of the uncertainty calculation will be
common for all determinands. Table 1 defines which instrument performance characteristics
should be included in the uncertainty determination. In each case the data used should be
from the most recent tests.