2003 June 3
Ralph Gillmann, FWHA;
In addition to showing people the confusing list of "systems"
of units, it might be useful to point out that many on the list
should not be called systems. Why? Because first, they are not
coherent and second, because they are not complete.
In the work of ASTM Committee E43 on SI Practice, I never use
"system" with inch-pound units. I suggest that you likewise list
"inch-pound units" as a general name for any set of units which uses
the inch and the pound, regardless of other units in the set.
You might also say that a contract which calls for "inch-pound"
units (or any one of the others on your list) might have a legal
problem in court because there are only weak legal definitions of
the units. Most inch-pound units have sizes provided by NIST but
"Are they legal?" could be argued.
Good luck.
Robert H. Bushnell PhD PE
