Change Log

Version 2.1

This fixes 4 defects of the specification itself. No new units.

• #185 tan100 defined inconsistently
• #183 Fix typing error for weber quantity kind
• #184 Canonical form not described
• #189 Two concerns on syntax tree

Version 2.0.1

Version 2.0

List of Issues Resolved

• Emergency minor release 2.0.1 on 13-NOV-2015 to fix the exponent of Planck's constant. #175
• ucum-essence.xml had elements in no name space. This was obviously a bug. It was resolved, not an emergency, but would have been more difficult to hold this minor fix back until 2.1 #157

Version 1.9

List of Issues Resolved

New units

tex	1	g/km	metric	tex
[den]	1	g/9/km	nonmetric	Denier
[anti'Xa'U]	1	1	nonmetric	arbitrary anti factor Xa unit
[EID_50]	1	1	nonmetric	arbitrary 50% embryo infectious dose
[Amb'a'1'U]	1	1	nonmetric	arbitrary allergen unit for Ambrosia artemisiifolia
[Lf]	1	1	nonmetric	arbitrary Limit of flocculation
[D'ag'U]	1	1	nonmetric	arbitrary D-antigen unit
[FEU]	1	1	nonmetric	arbitrary fibrinogen equivalent unit
[ELU]	1	1	nonmetric	arbitrary ELISA unit
[EU]	1	1	nonmetric	arbitrary Ehrlich unit
[foz_m]	30	mL	nonmetric	metric fluid ounce
[cup_m]	240	mL	nonmetric	metric cup
[tsp_m]	5	mL	nonmetric	metric teaspoon
[tbs_m]	15	mL	nonmetric	metric tablespoon
[oz_m]	28	g	nonmetric	metric ounce
[degR]	5	K/9	nonmetric	degree Rankine

Changed Units

Exact Constants

The following units are modified to turn constants which were stated of limited precision to exact. This is indicated by removing the decimal point from the number. If a number has a decimal point, it is considered having this number of significant digits, hence limited precision. If there is no decimal point (and magnitude adjusted in the exponent) it is considered exact.

[g]	980665e-5 (was: 9.80665)	m/s2	metric	standard acceleration of free fall
m[H2O]	980665e-5 (was 9.80665)	kPa	metric	meter of water column
Ci	37e9 (was: 3.7e10)	Bq	metric	Curie
[car_m]	2e-1 (was: 0.2)	g	nonmetric	metric carat

Corrected Constants

[Ch]	1	mm/3 (was: mm/[pi])	nonmetric	Charrière
AU	149597.870691	Mm	nonmetric	astronomic unit
[drp]	1	ml/20 (was: ml/12)	nonmetric	drop

Version 1.8.2

The major change of this release is the establishment of a class of "arbitrary units" which are no longer simply dimensionless. This is to protect the false assumption that one could convert measurement values expressed in some arbitrary unit into one in another arbitrary or dimensionless units.

Version 1.8

List of Issues Resolved

New units:

[wood'U]	1	mm[Hg].min/L	nonmetric	Wood unit
[IU]	1	[iU]	metric	arbitrary international unit
[BAU]	1	1	nonmetric	arbitrary bioequivalent allergen unit
[AU]	1	1	nonmetric	arbitrary allergen unit
[PNU]	1	1	nonmetric	arbitrary protein nitrogen unit
B[10.nV]	*	2lg(10 nV)	metric	bel 10 nanovolt