Table 2.

The example of extensional definitions (EDs).

Extensional attribute	Example	Value of information for meaning and mapping
Local description	“Creatinine, 24 hr urine”, ”Sodium urine”	Provides a human readable meaning for the test
Mean	1.46,137	Mean - the average value for quantitative tests. Provides information for reviewing quantitative tests.
Standard deviation	0.54, 7.02	Standard deviation - a measure of the physiologic consistency of the values of Quantitative tests
Units of measure	g/24 h, mmol/L, mg/dl	Units of measure - provides scale information. Sometimes it also provides time information (e.g. g/24h implies 24 hour)
Coded variables	Yellow (45), Negative (1345), Rare (697), 1+(143)	After grouping the same tests in each institution by their local codes, we calculated the frequency of each coded variable.
Frequency	50, 184	Frequency - implies whether tests are frequent (e.g. biochemistry tests) or rare (e.g. allergen test)