One or more refinements may be added to a concept to qualify it. This is done by putting the concept to be qualified before a colon and the qualifying expression after. The qualifying expression is of the form "attribute = value". The example below describes an operation to remove an ovary (i.e. an 'oophorectomy') using a laser.
Where more than one qualifying attribute is required, these can be separated using a comma. The example below describes the removal of an ovarian structure using a laser device.
Refinements may also be applied to a conjoined concept. For example, the following two expressions are equivalent (because an 'ulna' is a bone in an 'upper limb'):
313056006 |Epiphysis of ulna| : 272741003 |Laterality| = 7771000 |Left|