 An example based on

 'Enhancing Data Interoperability with Ontologies, Canonical Forms, and Include Files'

 by Roger L. Costello costello@mitre.org August 10, 2003

 ( http://www.xfront.com/interoperability/CanonicalForms.html )
someagent measures somequantity in someunits
not : the canonical measure of thatquantity is thoseunits
one unit of thatquantity measured in thoseunits converts to a canonical somenumber somestandardunits

thatagent sending one unit of thatquantity in thoseunits should first convert it to thatnumber thosestandardunits
thisagent measures thisquantity in theseunits
================================================
Agent A length kilometers
Agent A time seconds
Agent A speed kps
Agent B length miles
Agent B time hours
Agent B speed mph
one unit of somequantity measured in someunits converts to a canonical somenumber somestandardunits

the canonical measure of thatquantity is thosestandardunits
one unit of thisquantity measured in theseunits converts to a canonical thisnumber thesestandardunits
==========================================================================================================
length miles 1.609344 kilometers
length meters 0.001 kilometers
time minutes 60 seconds
time hours 3600 seconds
one unit of length measured in miles converts to a canonical somenumber1 kilometers
one unit of time measured in hours converts to a canonical somenumber2 seconds
thatnumber1 / thatnumber2 = somequotient
thatquotient rounded to 5 place(s) after the decimal point is somenumber

one unit of speed measured in mph converts to a canonical thatnumber kps