The following is based on a paper given by Ralph Burns at a Symposium of the Electronic Power Research Institute in Dallas.
Any human communication is subject to misinterpretation.
To minimize the likehood of being misunderstood, the engineering profession relies on mathematical symbols, definitions, standards, specifications and procedures. These agreed-upon tools help to ensure that information can be unambiguously transmitted from one person to another. The receptor individual must infer a meaning and what is thus inferred may not have any basis. Four phrases currently used in the valve industry are open to misuse because their meaning is not clearly spelled out. Each of these needs to be examined to determine what it means or is believed to mean.