The following terms are used here and in literature elsewhere to discuss reference materials.

All | # A B C E I J M N O P Q R S T U W
There are currently 2 names in this directory beginning with the letter W.
Westgard Rules
Borrowed from pathology, these are multi-rule, QC rules and utilise trend and bias to determine whether a process is in control. The advantages of multi-rule QC procedures are that false rejections can be kept low while at the same time maintaining high error detection.
wt.%
SI unit equivalent: wt.% (weight per cent) ≡ % (mass fraction).