Mapping pset value from a parameter or another ? Mapping using built in parameter name ?

Hello,

I have looked into source forge wiki and other sources but I did not find how to map 2 different parameters depending of which one is available in the object to the same pset property.

# Case
I want to map duct width and height for rectangular ducts and diameter for round duct. I use parameter mapping table.
## Works
_Warning: parameters name in French_
Only for rectangular ducts:
```
Pset_DuctSegmentTypeCommon NominalDiameterOrWidth Largeur
Pset_DuctSegmentTypeCommon NominalHeight Hauteur
```
Only for round ducts:
```
Pset_DuctSegmentTypeCommon NominalDiameterOrWidth Diamètre
```
## Does not work
Mapping both rectangular and round ducts:
```
Pset_DuctSegmentTypeCommon NominalDiameterOrWidth Largeur
Pset_DuctSegmentTypeCommon NominalHeight Hauteur
Pset_DuctSegmentTypeCommon NominalDiameterOrWidth Diamètre
```
Only the width and height is mapped. Not Diameter.
```
Pset_DuctSegmentTypeCommon NominalHeight Hauteur
Pset_DuctSegmentTypeCommon NominalDiameterOrWidth Largeur | Diamètre
```
Only height is mapped
# Question 1
Is it possible to map with a parameter or another ? If yes, how ? If not, how to solve above case to be able to correctly export parameter values to IFC standard psets ?
# Question 2
Is it possible to map using BuiltInParameter names instead of localised name ? It would allow to have an IFC standard mapping table. If yes, how ? If not would it be possible to add this possibility in next version ?

Start by reproducing the parameter mapping table cases described in the issue for rectangular and round ducts. Review the exporter’s mapping behavior and determine whether conditional fallback mappings and BuiltInParameter names are supported; done means the supported behavior or a clear implementation scope and workaround are documented.

Written by the indexing model from the issue text.