DCAT already supports these as properties of Dataset/Catalog using dct:temporal and dct:spatial respectively. 

I suggest including them as optional properties. 

In Draft 1, they are proposed as optional already -- spatial for both Dataset and Catalog, temporal for Dataset.

Actually, the issue was about the max cardinality for this properties (1 or many?) which is not explicitly specified in the draft.

See related issue.

My proposal would be to give all properties cardinality unlimited.

I agree with Makx. Unlimited cardinality.

The proposed resolution is to add clarification in chapter 7 that all properties have unlimited cardinality; mandatory properties 1..n, optional properties 0..n.

All properties with unlimited cardinality; mandatory properties 1..n, optional properties 0..n. could be quite confusing in general and also a relevant problem in same cases. Let's see some examples:

- Multiple descriptions or titles for a given Instance.

- Multiple identifiers for a given Dataset.

- Multiple release dates for a given Dataset or Catalog. 

- Multiple licenses for a given Distribution.

- Multiple byteSizes for a given Distribution.

and so on...

I think a more detailed case-by-case analysis may be needed for cardinality.

Yes, you are right. I will include a proposal for cardinality for all properties in the Application Profile in the next version.

On your specific points:

• mulitple names and descriptions are possible to allow for parallel language versions
• mulitple identifiers are possible to allow for local identifieres, DOIs, ARKs and other types of identifiers
• mulitple release dates would indeed not be useful
• mulitple licences for the same distribution would indeed be a problem
• byteSize is not in the Application Profile

Cardinalities have been specified in Draft 2.