According to the new EDTF specification at #209, season qualifiers should 
be enclosed between less-than and greater-than characters. In Annex A, 
though, they are enclosed within quotes. I consider both of them quite 
error-prone when used within XML and therefore, I suggest to enclose them 
within parentheses, which easily can be included in both text nodes and 
XML attributes.

Furthermore, the specification does not define the datatype of such a 
qualifier. For machine readability reasons (for example further LD 
conversions or comparisons), I would suggest to define the datatype of 
season qualifiers as URIs. This would also lead to higher recalls in 
semantic queries and alleviate the NLP difficulties occurring when 
searching strings.