[UDUNITS #CEG-308566]: definition of 'dram' in udunit2-common.xml

John,

I agree with the changes. The things to consider are
    1. Each name should unambiguously identify a unit;
    2. Each symbol should unambiguously identify a unit;
    3. Long names (e.g., "avoirdupois_dram") should be supported.

> A nit from working through definitions of all the units (zowee).
> 
> The specification of dram seems to have an inconsistency. I include here the 
> entry for both fluid dram and dram, with the modifications to include 
> comments and definitions.
> 
> > <unit>
> >    <comment>exact</comment>
> >     <def>US_fluid_ounce/8</def>
> >     <aliases> <symbol>fldr</symbol> </aliases>
> >     <definition>unit of volume for liquid measure in the apothecary system, 
> > equal to 1/8 liquid ounce; corresponding name is fluid dram</definition>
> > </unit>
> > <unit>
> >     <comment>exact</comment>
> >     <def>US_fluid_ounce/16</def>
> >     <aliases>
> >         <name> <singular>dram</singular> </name>
> >         <symbol>dr</symbol>
> >     </aliases>
> > </unit>
> 
> While the fluid dram specification matches my references, the dram seems to 
> be one of the following:
> * an avoirdupois unit of mass (and so should not be based on fluid ounces) 
> [1] [3], or
> * an apothecaries unit of mass (and so not based on fluid ounces, and only 
> 1/8 ounce apothecaries, which is a troy ounce not a US ounce) [2] [3].
> 
> All references to the use of dram as a fluid measure call it a 'fluid dram' 
> and make it 1/8 fluid ounces. I can't find anything on the web that matches 
> 1/16 US fluid ounce..
> 
> So this def should be changed to match a real dram. I think the first 
> definition of these two, as we already have the apdram defined, and the first 
> definition seems more useful. So the result would be as follows, and moved 
> into the mass section:
> 
> > <unit>
> >     <comment>exact</comment>
> >     <def>avoirdupois_ounce/16</def>
> >     <aliases>
> >         <name> <singular>dram</singular> </name>
> >         <symbol>dr</symbol>
> >     </aliases>
> >     <definition>unit of mass in the avoirdupois system (the system commonly 
> > used in the United States)
> > </unit>
> 
> 
> OK? (I can submit this change as I go along.)
> 
> John
> 
> 
> [1] National Institute of Standards and Technology (October 2011). Butcher, 
> Tina; Cook, Steve; Crown, Linda et al. eds. "Appendix C – General Tables of 
> Units of Measurement", page C-6
> [2] National Institute of Standards and Technology (October 2011). Butcher, 
> Tina; Cook, Steve; Crown, Linda et al. eds. "Appendix C – General Tables of 
> Units of Measurement", page C-7
> [3] WIkipedia entry https://en.wikipedia.org/wiki/Dram_(unit)  (what, 
> Wikipedia isn't always perfect?)


Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: CEG-308566
Department: Support UDUNITS
Priority: Normal
Status: Closed