[CF-metadata] cf-conventions-dimensionless coordinates

[Hand, Brian]

Thanks Jonathan for the response.
 
I just wanted to get more clarification about standard_names in general.  Johnathan mentioned this was an omission, meaning a unique formula is associated with certain standard_names that represent dimensionless coordinates.  I ask because I wasn't sure if it was possible to define a formula or those were set by the use of the standard name and really the only wiggle room you have is in the variables you choose for the formula terms?  The equation proposed looks good, though I think for our model at least we define 0 as the surface and 1 as the bed, but  could be mistaken.  
 
Thanks,
Brian.