This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
Jim, > I want to use UDUnits2 with a Chemical Engineering simulator called Aspen > Plus. Aspen Plus doesn't require coulombs or farads, but it represents > Fahrenheit and Celsius with F and C. I thought adding these definitions > would just be a matter of editing the udunits2-common.xml file like so: > > ... > <symbol>℉</symbol> <!-- DEGREE FAHRENHEIT --> > <name> <singular>fahrenheit</singular> </name> > ... > > To > > ... > <symbol>℉</symbol> <!-- DEGREE FAHRENHEIT --> > <name> <singular>fahrenheit</singular> </name> > <name> <singular>F</singular> </name> > ... > > And maybe I would have to delete coulombs and farads out of the > udunits2-derived.xml file. However, any attempt to do any of those things, > the deletion of farads or coulombs, or the addition of new names "F" or "C" > and udunits2 appears to fail to parse the XML file. > I don't think I'm messing up the XML, because I can add additional, more > unique, names to Fahrenheit, like "earwax" or "degrees_Jim." But "F" and "C" > seem to be illegal. I haven't dug into the UDUnits code yet, does anyone > know how to get this to work? I STRONGLY advise against doing this. Your datasets will loose interoperability and the workarounds are trivial (use instead "deg_C", "celsius", "\xB0C", or any of the other identifiers, for example). I hate to say it but, in my personal opinion, the authors of Aspen Plus are exposing a lack of knowledge, professionalism, and/or rigor on their part by not adhering to internationally agreed-upon standards. If you insist on changing the standard definition of, for example, the symbol "C", then you will have to modify all occurrences of that symbol in the database: cd $prefix/share/udunits grep -w C udunits2-*.xml udunits2-accepted.xml: <def>2.58e-4 C/kg</def> udunits2-common.xml: <def>1.602176487e-19 C</def> udunits2-common.xml: <def>9.64957e4 C</def> udunits2-common.xml: <def>9.65219e4 C</def> udunits2-common.xml: <def>9.648531e4 C</def> udunits2-common.xml: <def>3.335640e-10 C</def> udunits2-derived.xml: <symbol>C</symbol> udunits2-derived.xml: <def>C/V</def> udunits2-derived.xml: <symbol>°C</symbol> <!-- DEGREE SIGN --> The last entry should be left alone; the 3rd-to-last entry should be deleted; and all other entries should have the "C" replaced with "coulomb". > Thanks, > Jim > > _______________________________________________ > udunits mailing list > address@hidden > For list information, to unsubscribe, or change your membership options, > visit: http://www.unidata.ucar.edu/mailing_lists/ Regards, Steve Emmerson Ticket Details =================== Ticket ID: ZZS-676605 Department: Support Priority: Normal Status: Closed