Alan Garny wrote:
>> Again, this is a feature that it would be useful to be able to turn on
>> and off. However I think in most cases the software will not be smart
>> enough to figure out what the units should be.
> Wrong, it can easily be done. I was about to work on that in COR when Peter
> got me to move over to "PCEnv". Check also JSim, it does units conversion
> and, as far as I know and can tell, it does a pretty good job at it.

This only applies if the model was initially coded with the intention 
that such a feature be used. If the model empirically works despite 
units issues, which is probably quite common, attempting to 'fix' the 
model will actually break it (for example, it might have conversion 
factors in there, but marked as dimensionless). It would require a lot 
more intelligence from a tool to work out if the conversion factors are 
there, perhaps folded into other conversion factors, and add the 
appropriate metadata. This is why doing automated conversions at this 
level would be a bad idea for a CellML tool.

In light of the fact that:
a) from a specification point of view, it is much better to make people 
write good equations and validate them than to have modellers rely on 
some feature which converts them, given that a single component is 
designed by a single person, and
b) the current specification isn't supposed to request that such 
conversion be performed automatically (although it could be construed in 
such a way), and changing something this major will cause problems with 
models which already work empirically,

I would recommend that we keep the status quo and not perform 
conversions within equations.

Best regards,

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