Terry Simpson asked in USMA 23354:
Joseph B. Reid wrote:any intelligent reader of the SI brochure would have no difficulty in distinguishing SI from metric units that are now obsolete. These units are listed in Tables 9 and 10.I clearly have difficulty.Are you saying that all units listed in table 9 and 10 are obsolete?
The BIPM brochure in section 4 says:
"The inclusion of tables of non-SI units in this text does not imply that the use of non-SI units is to be encouraged. With a few exceptions discussed below, SI units are always to be preferred to non-SI units. It is desirable to avoid combining non-SI units with the units of the SI; in particular the combination of such units with SI units to form compound units should be restricted to special cases so as to retain the advantage of coherence conferred by the use of SI units."
Section 4.2 contains "Table 9. Derived CGS units with special names" and "Table 10. Examples of other non-SI units". A footnote adds "The relation of these units to the SI should be specified in every document in which they are used."
In USMA 22314 Terry states "NIST wrote that it is confusing and redundant: a) to use the term "SI metric" system because it implies that there are metric systems other than the International System of Units (SI)," This is plainly wrong. The term "metric systems" covers much more than SI.
Joseph B. Reid
17 Glebe Road West
Toronto M5P 1C8 Telephone 416-486-6071
