Ontology quick comments

Very quickly scrolled through https://github.com/buildingSMART/bSDD/blob/master/RDF/preview-bsdd-rdfs-0.3.ttl and provide some quick comments:

First note. I'm not an expert on ontology development.

No domains on properties. This makes it quite hard to understand and use probably.

Double:

```
bsdd:ReplacedObjectCode a rdf:Property ;
skos:prefLabel "Replaced Object Code"@en ;
rdfs:range xsd:string .

bsdd:replacingObjectCode a rdf:Property ;
skos:prefLabel "Replacing Object Code"@en ;
rdfs:range xsd:string .
```

Vvisual:

```
bsdd:VisualRepresentationUri a rdf:Property ;
skos:prefLabel "Vvisual Representation URI"@en ;
rdfs:range xsd:string .
```

Pparent:

```
bsdd:ParentClassificationCode a rdf:Property ;
skos:prefLabel "Pparent Classification Code"@en ;
rdfs:range xsd:string .
```

Uunit:

```
bsdd:Uunit a rdf:Property ;
skos:prefLabel "unit"@en ;
rdfs:range xsd:string .

bsdd:QudtUunit a rdf:Property ;
skos:prefLabel "QUDT reference"@en .
```

Everything range string, I'd look for ways to enforce more consistency in the data, e.g prevent Netherlands/Holland/NL/nl/The Netherlands. I understand that there needs to be a reasonable sync between RDF <-> database, so it might not be possible, to normalize everything into classes (or maybe it is...).

```
bsdd:CountryOfOrigin a rdf:Property ;
skos:prefLabel "Country Of Origin"@en ;
rdfs:range xsd:string .
```

I wouln't expect relationship as a class. What's the intention here:

```
bsdd:ClassificationRelation a rdfs:Class ;
skos:prefLabel "ClassificationRelation"@en .
```

XSD can be imported as an ontology:

```
bsdd:MinInclusive a rdf:Property ;
skos:prefLabel "Min Inclusive"@en ;
rdfs:range xsd:float .

bsdd:MaxInclusive a rdf:Property ;
skos:prefLabel "Max Inclusive"@en ;
rdfs:range xsd:float .

bsdd:MinExclusive a rdf:Property ;
skos:prefLabel "Min Exclusive"@en ;
rdfs:range xsd:float .

bsdd:MaxExclusive a rdf:Property ;
skos:prefLabel "MaxExclusive"@en ;
rdfs:range xsd:float .

bsdd:Pattern a rdf:Property ;
skos:prefLabel "Pattern"@en ;
rdfs:range xsd:string .
```

skos:note/rdfs:comment?

```
bsdd:Description a rdf:Property ;
skos:prefLabel "Description"@en ;
rdfs:range xsd:string.
```